I'm not a big fan of Vegas (actually that's an understatement), but I have to say you may just want to consider it. As others have pointed out, since the USD is (rather spectacularly) in the tank, you'll get a lot of bang for the buck. Vegas is kitsch, tawdry and fake but it does have a few nice hotels, some great restaurants and fun shows. The gay scene is pretty lame though. I say go to Vegas and embrace the cheese. See the Liberace museum-or something along those lines. On the serious side, check out Ka or O (they are truly awesome shows), have a few nice meals. Go with the flow. Most of the nicer hotels will have a spa, so treat yourself to massage. Since none of this will come cheaply, now is probably a good time to go. US travel won't always come at bargain basement prices.

As for San Diego it's a truly wonderful place and will always be there when you tire of Vegas.