In the interest of painting a little more color in for some members regarding what Hyatt's brands are and what they stand for, I thought I'd create a dedicated thread with my thoughts and create a space for others to chime in. Maybe the mods can make this a sticky so that members can easily access it?

Without further ado:

Hyatt classifies their brands in three distinct buckets: Timeless Portfolio, Boundless Portfolio and Independent Collections, with the "premiumness" of their brands ranked from most to least premium accordingly. The Timeless Portfolio consists of their classic brands, Boundless encompasses their lifestyle offerings and Independent Collections is for all their independent, unbranded hotels.

Timeless Portfolio

• Park Hyatt is Hyatt's flagship offering, consisting of luxury properties that are smaller in size, residential in feel with muted color schemes of beiges and browns and personalized service. Competitors to this brand are St. Regis, Ritz-Carlton, Four Seasons and Mandarin Oriental.
• Miraval is a luxury wellness brand consisting of expansive resorts that are fitted with plush rooms, spas with large offerings, menus that are health-oriented and a guiding principle encouraging guests to disconnect [i.e. having little cloth bags to place one's electronics in and gently discouraging guests from utilizing them during their stay]. Miravals are all-inclusive, but alcohol is not included within their package as it isn't considered conducive to the wellness experience - but it is available on their properties at a supplementary charge.
• Characterized by their extensive meeting spaces and bold architecture, Grand Hyatt is a luxury brand that competes with JW Marriott, InterContinental and Fairmont. Hotels tend to be on the larger side [250 rooms and above] and they tend to include multiple F&B offerings with a range of cuisines on offer to guests.
• Hyatt Regency is Hyatt's largest brand, and is an upper-upscale brand consisting of hotels that are primarily ranked as four- and five-star. These hotels have the flexibility of being small or mega-properties, and are supposed to cater to a wide audience of guests including those looking to vacation, those looking to work and those just passing through. Competitors include Hilton, Sheraton and Marriott.
• The plain Hyatt brand is an odd duck in the portfolio, consisting of allegedly upper-upscale hotels that don't have another home in the Hyatt family. The few properties in there are usually dated, on the way out of Hyatt or are marketed as "Hyatt" while they complete transitions to other brands [i.e. Park Central San Francisco, which is currently a Hyatt but will become a Hyatt Regency, or the Parker New York which will become Thompson Central Park]. Corporate apparently wants to weed this brand out since it doesn't stand for anything, and move the few hotels in the collection to different brands.
• Hyatt Zilara is an all-inclusive, adults-only offering of larger resorts in beach destinations in México and the Caribbean.
• Hyatt Ziva is an all-inclusive collection of beach resorts operating in the same regions as Zilara, but are family resorts open to all. Ziva and Zilara properties often sit side-by-side, but Ziva properties can also be standalone - i.e. Los Cabos, and the upcoming one in Barbados.
• The answer to Courtyard and Hilton Garden Inn, Hyatt Place was born out of Hyatt's 2004 acquisition of AmeriSuites, and consists of select-service, upscale hotels catering to mid- and upper-income guests. Hotels are very formulaic in design and generally devoid of much imagination, with spacious rooms that include an L-shaped sleeper sofa, Hyatt's signature bedding and shower-only bathrooms.
• Acquired by Hyatt in 2006, Summerfield Suites would go on to become Hyatt Summerfield Suites until 2012 when it was rebranded Hyatt House. This is an extended-stay, select-service brand in the same vein as Residence Inn and Staybridge Suites, with a variety of rooms including Dens for short-stay guests that only have microwaves and kitchenettes, to studios and suites with fully-equipped kitchens for longer-stay guests. Breakfast is free in most locations, and there are on-site facilities for working out and laundry. Incidentally, when the first Hyatt opened in 1957, that first property was called the Hyatt House.
• UrCove is a China-only brand developed in conjunction with the Chinese hospitality brand BTG Homeinns. UrCove is the lowest-positioned brand in the entire Hyatt hierarchy as the sole upper-midscale offering, and competes with the Hampton Inn family. Like Hyatt Place, designs are upscale but formulaic and derivative, and hotels offer basic offerings like a restaurant, a 24-hour gym, self-service laundry and meeting rooms.
• Hyatt Residence Club is a vacation ownership brand similar to Hilton's and Marriott's Vacation Club brands. As per Hyatt, "members pre-purchase time at a Hyatt Residence Club property and have the flexibility of usage, exchange, and rental. Hyatt Residence Club members can choose to occupy their vacation home, exchange time among other Hyatt Residence Club locations, trade their time for World of Hyatt loyalty program bonus points, or travel within the Hyatt system."

Boundless Portfolio

• Andaz sits at the top of the pyramid as a competitor to EDITION, W and SLS, and all their properties are supposed to be at the luxury level. Their hotels are centered around art, design and an abundant use of color inspired by the surroundings of the respective hotel's locations. Andaz, along with Hyatt Centric and Caption, is a home-grown Hyatt brand entirely developed in-house.
• Next up is Alila, whose luxury hotels are positioned in aspirational or unconventional destinations - "the road less-travelled", as they put it - and seek to create an environment where guests can reflect and recharge. Color schemes at Alila are more beige and natural, the spa forms a big part of their offering, they seek to utilize local traditions and materials in their F&B and décor, and sustainable practices that respect their local communities lead the brand direction.
• Thompson was inherited along with Alila, Destination and JdV in the Two Roads acquisition. Thompsons are luxury-class hotels characterized by a mid-century modern design aesthetic, and place an emphasis on destination F&B outlets. They compete in the same space as Hoxton and Kimpton, so expect lots of design-forward cues and a see-and-be-seen vibe.
• Hyatt Centric is positioned below Thompson as a four-star, upper-upscale [as opposed to luxury] brand with properties that are colorful and creative in design and feel, draw inspiration from their locations and are located in prime destinations. They're in the same operating space as Le Méridien, Renaissance and Canopy.
• At the bottom of the lifestyle ladder is Caption, which will be a three-star, select-service brand. The first two locations are confirmed for Memphis [a new-build] and Shanghai [a conversion of the current Pentahotel], and the hotels are conceived as being very casual and approachable, with an open-plan lobby that feeds into a restaurant/bar conducive to grab-and-go as well as dine-in, encouraging younger clients to come hang out in and rooms that are compact but have all the essentials. Caption is Hyatt's answer to Aloft, Moxy and Motto.

Independent Collections

• The Unbound Collection straddles the line between Marriott's Luxury and Autograph Collection brands - it's an upper-upscale/luxury brand that includes hotels that are not outright luxury-centric as LC, but it also has some proper luxury hotels above what you'd find at an Autograph like the Hôtel du Palais Biarritz and Hôtel du Louvre in Paris].
• The one brand I personally don't get the point of, Destination by Hyatt is an upper-upscale offering what Hyatt calls "a diverse collection of independent hotels, resorts, and residences that are individual at heart yet connected by a commitment to draw upon the true spirit of each location. Each property is purposefully crafted to be a place of discovery for guests through authentic experiences, unique design, and connections to the local community." The way I look at this, Destination includes some nice new resorts, some super dated ones and a bunch of residence properties that don't really participate in the loyalty program, and Hyatt would do good to simplify things by shuttering this brand and slotting their hotels either into Unbound or JdV and focus on building those portfolios out.
• Lastly, we've got JdV by Hyatt, which Hyatt picked up in the 2018 acquisition of Two Roads Hospitality, and formerly known as Joie de Vivre before Hyatt decided to rebrand it as JdV by Hyatt - which doesn't stand for anything unless you know the brand's history. Hyatt says this one competes with Kimpton and Autograph Collection hotels but the way I see things, JdV is aimed squarely at Tribute Portfolio: upper-upscale, neighborhood-themed hotels that don't need to have anything in common with other hotels in the collection, and are generally three- or four-star hotels with greater freedom in design and expression.

Honorable mention:

• tommie was intended to be a standalone upper-upscale brand under Thompson, and then under their former parent Two Roads Hospitality, with hotels that were in the same design theme as Thompson but with smaller rooms. When Hyatt acquired Two Roads, they initially planned to keep tommie alive, open the two pipeline hotels in Austin and Hollywood, and find ways to expand the brand... but then decided to kill tommie as a brand, open the one in Austin as a JdV and open the Hollywood hotel as the first Caption by Hyatt. Hyatt sat on that for a while, then reneged on that plan, decided to revert to the tommie branding for the Hollywood hotel and slot it under JdV the same way they're doing for Austin. The two tommies will live under JdV, and that's all we'll see from them and that brand.

khabah