i hear poker is a cinch in vegas so if you're a poker player, id go with that.
$500 isnt much, and if thats your limit, thats your limit. if you get up a few hundred, walk away. get something to eat and then start over with your initial buy-in money. vegas and other casinos make their money when you win and just keep playing and letting it dwindle away. also, if you're going to be drinking, and i suspect you will be heavily, try not to gamble too much. you dont want to make any rash decisions.
and girls. get some while you're there.