Enjoyable hotel stay every time!
For the last couple of years, I have stayed here on several occasions with the most recent the Roger Waters (Pink Floyd) concert. Prior to this stay, my girlfriends and I stayed here for my bachelorette soiree in the city. The hotel is conveniently located downtown San Francisco so, it's a great place to stay when I don't want to do the hour drive home to South Bay area. 
The rooms are clean, the beds are comfortable, and the amenities are predictable (and appreciated) Marriott. I have enjoyed the breakfast buffet here before and it was pretty tasty. You're also surrounded by so many food options that it's worth exploring if you want to be adventurous.
I'm sure there are many great places to stay in the city but there is something fantastic about knowing that where you will stay will be fine and comfortable, so you can enjoy the reason you're in the city!