We stayed at the Fairmont last summer on points. I grew up in SF. I now live about 2 hours east. We had points that we were going to lose so decided it would be fun to go to SF and do touristy things.
We had a blast. We went to Alcatraz, the Exploratorium, Fisherman's Wharf, Ghirardelli, rode the cable car, etc. I loved being back in the The City. The city sounds lulled me to sleep. Loved hearing the cable cars ringing their bells. The windows of the room opened up a bit so you could get fresh air, feel the moist air, and hear the cable cars go by. The noise, with the windows open, was a bit much for DH at night but he suffered through it so I could sleep like a baby. Noise wasn't an issue with the windows closed.
We had a Tower Room on the second floor. It had a view of Coit Tower and Alcatraz. Saying the second floor is a bit misleading. It was second floor compared to the lobby entrance. However, the Fairmont is on a steep hill. So, our 2nd floor room was probably about 6 floors about street level.
I'd guess that the higher up rooms would have a view of the GG bridge in addition to Coit Tower and Alcatraz but we were too low. I wouldn't have traded for a higher up room though. I don't really like to be above the 7th floor in hotels.
One idea you might want to look into is the trying the Tonga Room restaurant at the Fairmont. It's got a great deal at Happy Hour. I don't remember the cost. It's like $6 or $7 per person and they have a nice little buffet set up with appetizers. I don't remember exactly what was offered but there were fresh veggies and things like pot stickers and wontons, and more. The restaurant has a pool in the middle with a little island that moves out where a band plays. They have rainstorms around the pool about every 30 minutes or so. My kids loved it. We ended up having dinner instead of doing happy hour. I'm guessing happy hour guests stay around the bar rather than sit near the pool but I could be wrong. Either way, you can still see the pool and the rainstorms from the bar area.
Another thing to remember is that parking is very expensive. I believe parking was something like $35-$40 a night.
We did walk from the hotel to Pier 39. It's downhill and looks closer than it is. We probably should have taken a cab. It was fine for me and DH but my kids were 7 and 4. We walked down the hill (I'm guessing about 15 blocks) to Pier 39, toured it, toured Alcatraz, walked to Ghirardelli, stood in line for at least an hour for the cable car, and my kids were exhausted. There was no way the 4 year old could have done all that without the stroller. My 7 year old did it without complaining but she was exhausted by the time we got back to the room.
Definitely buy tickets for Alcatraz in advance.
The walk to Union Square is easy. The walk back is tough especially if you are pushing a big 4 year old in a stroller.