Nice rooms, great staff, unique building
I haven't stayed in Courtyard by Marriott much lately, but based on this experience I will more. I agree with other reviewers that the staff was amazing. Friendly, helpful, and accommodating. The hotel is in an old converted bank that has more character than 99% of hotels. The room doors are even the originals and the meeting rooms are converted vaults. The location is convenient to most downtown places, but its a decent walk to the convention center or baseball stadium. We have a trade show in SD in 2013 and I hope to be at the same hotel.
Rooms: nice and big, very comfortable beds, flat screen TVs, free wired internet (no WiFi that I noticed, but I was always working at the desk). My room was on the 12th floor and had giant windows with a view of the area. Value was very good for the area. 
Bathroom: nothing remarkable, but clean and perfectly fine. 
Service: From the minute I got there, everyone was friendly and did everything they could to meet my requests. I never felt like a distraction or ignored in any way. I felt like a valued customer.
Location: about 1 mile from the convention center or Petco Park (Padres), tons of restaurants in walking. I didn't have a car (walked everywhere and loved it), but I think parking is somewhat of a hassle and expensive. Probably not much different than any other downtown hotel, I just very rarely stay in downtown hotels. Only bad comment on the location is that its sort of the dirtier end of the Gaslamp area and you should be prepared to be confronted by many homeless people. Some of the stores and restaurants in the immediate area are a bit on the seedy side (pawn shops, dirty little restaurants). If you walk a few blocks more, it gets better. None of this really bothered me, but it may not be what some people expect. 
Exercise room: I'd give it 4 stars. Far better than a typical Hampton Inn or Holiday Inn Express closet with some crappy 10 year old treadmill, but I've seen better. The machines were good (maybe 3 treadmills, 1 bike, all with internal TV, weights, etc) but the room was fairly warm even after I asked them to make it cooler. Its also odd that the TVs on the machines only get a few channels.