Home away from home
I love this hotel and use it as my primary for all business trips to SF. I'm in SF about three times a year and am disappointed if it is sold out. The location is great for views and its very close to my favorite restaurant, Nob Hill Cafe. Word of caution though. This hotel is at the top of a steep hill and sits above Union Square and the wharfs so be prepared to get some exercise or use a cab. The Powell St. cable car stops right by it as well. You can take BART into Union Square and then walk to Powell St. and catch the cable car. Get off at California St, which is exactly the corner where the hotel sits. 
As for the hotel itself, it has a very nice gym complete with free weights and several cardio units. The lounge for Marriott Rewards members is top notch with a killer view. I find the rooms comfortable and decorated with style. Price is about average for SF. I used to stay in the financial district and that's nice as well, but this feels more residential and a little more quiet. The wharf seems more family friendly to me.