I have stayed in all of the SF Starwoods multiple times. The best deal, by far, is when the St. Regis will offer you a superior room at the SPG50 rate (1000 points for up to 5 nights), which is $295/night. If you specifically ask for a quiet room (some of their rooms, especially in the higher categories, have more street noise), I believe this would be your best choice. They have a beautiful indoor pool that almost nobody uses; it will essentially be private for you. And the rooms are, by far, better than any of the alternatives.
The Palace would be my next choice for you. I don't ever remember any street noise there, and if you book one of the higher categories there should be plenty of room for a roll-away. They also have a pool. The rooms at the Palace are, IMHO, much nicer than at Westin Market St.
Le Meridien would also be good, but the location is not great and there is no pool.
I would put Westin Market St. next, and the St. Francis last. If you choose the St. Francis, I would definitely try for one of the rooms in the newer Tower. Everything at the St. Francis feels kind of run down, though, next to these other choices.