I think it depends on what you plan to do in SF. If the Modern Art Museum and Market Street (shopping) are of interest, then Marriott. Walking distance to Sheraton Palace for Sunday Brunch in the Garden Room (not to be missed for such a special birthday). Near Boulevard and One Market Restaurants. For dinner at Gary Danko's (the hottest), try early evening (no one in SF would dream of eating at 530) or the bar where you can order dinner. Most inner city cab rides run about $5 a pop. Hotel parking is steep for a rental car.
Marriott is known locally as the Jukebox! It has a great bar in the top of the bldg and, for history buffs, opened the night of the 1989 earthquake! A chandelier broke loose. That was the extent of the damage.