It's not quite the same thing but the Hyatt London Churchill gave me an executive suite when I used my suite upgrade cert. but then didn't actually take the certificate so I got a free upgrade from a standard room. I'm not sure if this was on purpose or not

Hyatt Regency Crystal City upgrades, I believe. At least I got one.

Regarding Hyatt IAD, I think they are an "all suite hotel" and they only have a couple really nice suites, the rest are just a bed areas set off from a sitting room area by a credenza. At least I think that's the case.

On my last stay at the ANdAZ Wall St. NYC (3 night NBT award stay, 4/17/10), I requested an Executive King room on the reservation. Though not "officially" a suite I guess, it is a very large corner room with a separate sitting area and TV... what passes for a suite at many lesser properties. My request was granted upon check-in without further inquiry.

My previous stay at this property (2/19/10) I received a Deluxe King upgrade (no requests made), which is a slightly larger room than the standard King. Experiences posted on the master thread for this property prompted me to try for the Executive King, and I was pleasantly surprised it was granted without question.

I'm not sure what a confirmed upgrade cert would procure at this property, I would be very curious... because it looks like the next level King Suite at this property is quite grand. I was very happy with the Executive King!

Hyatt McCormick Place, in Chicago, has a policy of upgrading Diamonds to suites, as previously mentioned. Where available, these tend to be the Skyline Suites - ridiculous double-doored sprawling things, on floor 30+. They're bascially a regular corner room, connecting with a vast (800sqf+) living-room with sofas, dining table, mini-kitchen and sweeping views of Chicago and the lake, along with another bathroom. (The bathrooms are regular-room bathrooms, so nothing too special there. But nevertheless - absurdly good.)

Grand Hyatt Seattle gives me an automatic (I don't have to ask) upgrade ~80% of the time. It's a fantastic hotel ^.

Hyatt Regency Bellevue has never given me an upgrade.

I used a cert to upgrade at Hyatt Regency St. Louis arch, the counter person told me they normally upgrade Diamonds regardless, so I probably wasted my cert. Although the hotel is very nice with good restaurants etc., the suite was spacious, but not particularly well decorated. If it weren't for the plasma tv's (2) and the bed, I would have otherwise thought I was staying at a Best Western.

Hi,

I stayed at Grand Champions at Indian Wells (Palm Springs) last week and was upgraded to a Penthouse Suite from my booking of the cheapest pre paid rate. Very happy with this property!

Hyatt Santa Clara
 

It was offered to me by front desk when I checked in at 8:30 p.m. on a recent Saturday night (hotel actually appeared to be pretty busy). Executive Suite, very nice! Furnishings & decor made it one of the best suites I've ever received. Even had a Cuisinart coffee maker, whole coffee beans & a Cuisinart grinder. As good as a view that one could hope for in Santa Clara :) I had been going to look for food elsewhere, but decided what the heck I'll enjoy room service in my nice suite.

The Hyatt Fairfax often gives me upgrades to a nice suite.

The Hyatt Dulles told me they try to do this.

The Grand Hyatt DC do not...

Hyatt Fairfax and Dulles are very similar buildings with (almost) all rooms being "suites", as described by Artemis above as: "just a bed area set off from a sitting room area by a credenza. " I've stayed at these properties probably about 20 times each over the past several years.

In my personal experience, I've never received anything more than the standard room "suite" at Dulles. At Fairfax, I have been given the bigger end semi-secular rooms about half the time, and once was upgraded to a very large suite (about the size of 3 standard suites).

I have also stayed at CC about 20 times over the past few years. A couple times I've been given a slightly larger "executive" room, and only a couple other times, I've been given a suite.

Huge potential
 

As already predicted, a potentially very useful thread has mutated into one highlighting mostly single experiences, aka one time experience = always suite upgrade.

It would be helpful, if this thread continues with properties that have a proven track record or 'official' policy internally to upgrade a Diamond to a suite, whenever possible.

So far, one can say for sure that the:

Regency McCormick
Regency Orange County
Elliott Grand Seattle

have such a record/policy

I like to add the

Regency Bonaventure Weston

to that list, a suite upgrade is listed as a NOR1 upgrade free of charge ^

Certain Hyatt properties have an all junior suite layout or have quite a number of studio rooms/junior suites, e.g.

Hyatt at Dulles (IAD)
Hyatt Fair Lakes / Fairfax ( with views of IAD, IIRC ;) )
Hyatt Lisle

Some Hyatt properties are trying to upgrade to suites, when the RC is closed:

Grand Champions Indian Wells

Using E-standby now, their default upgrade is for the Ambassador Suite (500 square feet) -- if of course its available.. looks quite nice. Generally 1.5 - 2x the price of a normal room, so a pretty good diamond upgrade.

My experiences this year....
 

2 out of 3 suite upgrades at the Andaz West Hollywood.
This is one of my favorite properties in LA.

7 out of 7 at Orange County - Garden Grove
I'm not sure what a non-suite looks like.

1 for 1 Mission Bay, San Diego
Great corner suite

0 for 1 Westlake, Ca.
Nice corner room but no suite

0 for 1 Grand San Francisco
nice corner room but no suite

1 for 2 Newport Beach
I had a suite with private swimming pool.....nice

0 for 1 Olive 8, Seattle
nice room, no suite

1 for 1 Lake Tahoe
upstairs in cabin - very nice

needless to say...no certs were used

Received a Suite at the Hyatt Fisherman's Wharf in SFO...

Of three stays at the ANdAZ WeHo, I have never received a suite upgrade. :(

In fact, your reporting of frequent suite upgrades, sans certificates, is surprising since there was a period when they were not even allowing the use of upgrade certificates (as reported in the property master thread). The view rooms are nice though (the standard upgrade), and I think it is a great property as well.