We are going next week. What to do really depends on what you're into. We like to eat, so we are going to a bunch of good restaurants. And we like to gamble, so most of our time will be in the casinos, although we are going to one show.
If it's you and a bunch of guys, the first day you get there, I would make a grocery order from Von's. They will deliver for free on your first order. Get some water, snacks, and some beer for the room/walking around with. This is good because you can leave your room with it and not have to wait for a server in the casino. Don't get glass bottles because they aren't allowed on the strip anymore.