I was born and raised in SF, now live just south of the city. I go up to the city often, and when I spend the night I prefer the Hyatt Regency.

Grand Hyatt:
The GH is located in the heart of the city "Union Square", this is one of the top shopping districts in the country, SOMA, Chinatown, Nob Hill are located just a few blocks away. But... the hotel is dated, and rooms are small and can appear a little worn. I called last February they said renovation was planned for later this year. . It's great location but the hotel is a dump, this place needs renovation badly.

Hyatt Regency, Embarcadero:
The Regency Club Level at the Hyatt Regency was renovated 2 -3 years ago. It's sort of like a hotel with in a hotel. The rooms have been nicely done, beautiful bathrooms with a t.v. located in the mirror. The Club Level Rooms with a balcony are the best. These rooms offer stunning views of the bay and the city. I would recommend requesting a room closet to the bay on the 16th floor, and if these are not available the rooms on the other side of the hotel have no balcony but offer stunning views of the Bay Bridge. Again I stress you want to be in a room toward the bay end of the hotel.
The restaurant and the gym have also been recently renovated. The Stay Fit Gym has been relocated to a much larger space on the lobby level.

Although you said you would spend little time in the club... The Club at the Hyatt Regency is stunning, one of the best in the Hyatt Chain. They offer a plentiful breakfast and evening hors d'oeuvres, each night with a different theme. The view from the lounge would be your WOW factor. I often sit up there on my lap top watching the ships, and sail boats go by. A few times I have been up there I have heard couples cancel their dinner reservations to spend more time in the club.

The Regency is located in the Financial District on the Embarcadero, with the Ferry Building being the main attraction. At the Ferry Building there are a few nice restaurants, shops, and a Farmers Market every Saturday Morning. Many tourist and locals love to walk. Jog, skate, and bike along the Embarcadero it’s great for people watching, and offers great views of the city, and the bay.

Embarcadero Station is located right outside the hotel. BART, MUNI LTR, Cable Cars, Street Cars, and buses are located just steps from the hotel. All the MUNI Light Rail Vehicles serve this station and can take you too many of the colorful neighborhoods the city is famous for. If you’re not into public transit, cabs are easy to get . Union Square, North Beach, SOMA, and Chinatown are about a 20 -30 minute walk from the hotel

Sorry for the long reply, but I know and love this city, and have spent time at both hotels. I hope this helps. Any more questions feel free to ask.