How many nights?
There's a couple of things that come to mind like Citi Hilton Reserve (2 weekend nights) Chase Hyatt (2 nights anytime) - but both of these seem like a waste of free unrestricted nights when there are better places to use them like Japan, France, Australia, Indonesia, etc. If you don't plan any travel like that they'd be fine.
There's the Chase IHG for 80k points, but I think the IC in SF is like 50k/nt. The Sapphire Preferred for 40k would almost be enough for 3 nights (15k/nt) at the Hyatt Regency. INK has a higher bonus which would mean at least 3 nights in the HR if you can get the card and meet the spend. I think the general guide line was blurry with Chase and included up to 3 cards in a month (
link).
Airbnb is also a good option in SF. Check out the SF thread in EDF for info.