Just some odds and ends:
3 or 4 days will not get you bored in LA. You do not need to venture to San Diego. Hell, it can take you 3 or 4 days to hit all the requisite burger places.
I like Las Vegas a real lot, but there, I think 2 or 3 days is enough. In December you cannot lay around at the pool if you were so inclined. In other words between meals and gambling there is not a whole lot to do.
I like to play poker and craps for the most part. You can make $100 last a LONG time at a 1-5 stud table, but it will go pretty quick at a $3-6 hold em table. Craps is a high capital game (I think) but a hell of a lot of fun and adreniline--and there is nothing like the feeling of being at a hot table. I think even if you count cards, you need several $$$ to play out the streaks. Card counting does not mean you sit down and win. It means you play to your advantage when you percieve an advantage, but you might still not win with a favorable count. You need a bankroll.
I've used Priceline twice in the last few weeks with enormous success. As long as you have flexibility as to where you want to stay in a town, it is the best option (IMHO).
If you pick Vegas, Miami, or LA (or Milwaukee) (or Austin), I can pip in with more advice.
Rob
Think Yiddish, Dress British - Advice of Evil Ronnie to me.