I go once a year for a trade show, and I take along a bunch of DVD's and catch-up on all the movies my wife doesn't want to watch.
I usually play one Hold 'em tournament ($30 in Excalibur's poker room) and that's it. I'm too tight for the big shows or even the titty bars.
If it's your first trip, you can just "see" everything for free (Bellagio fountains, etc.). Also, inside MGM you can actually get paid for being on a TV panel. You watch some 22 minute show and then sit around and tell 'em what you think.
Good luck!