IMHO, SFO isn't even optimal use of the miles because one could possibly net 5k earned miles on the RT on a $200ish ticket. By comparison, a ticket to, say, HHH, would cost the same 20k but would have earned fewer miles.

SFO can be easily visited at a future date for $200. Belize, OTOH, is impossible to reach for 25k miles by any other means.

I see the priority as making good use of the miles, with the actual destination secondary. DCA is nice for a weekend-- but is it a good use of miles from PHL? Nope. If we're looking at US destinations, and knowing Southwest-match fares from PHL are regularly around $200, let me think of some interesting non-Southwest destinations. Denver? Minneapolis?? Key West still sticks out- but with the recent weather, may be iffy. Montreal, even-- taxes will be lower on an award than on a paid ticket so there is inherent value there. Still, for value on the miles you spend, it's hard to beat the 25k Latin America/Caribbean awards.

The choice is up to you, though.