Some of my favorite things to do in Vegas:
1. Go to the Voodoo Lounge at the top of the Rio. Go early because if you go later they will hit you with a cover charge. It is so spectacular to watch the sunset and the lights of Vegas turn on. It is simply magical.
2. Go to the Paris and look at all the shops. There is a bar called the Nepolian (or something like that) during happy hour. They serve free sandwiches with drinks...helps soak things up
3. If you plan on visiting many casinos at one time, allow time because it will exhaust you. Some that you can hit in one morning: New York, New York, MGM, Monte Carlo, Excalibur, and the Luxor.
4. The best meal we had was at Prime located in the Bellagio. It was pricey but very good.
5. Don't forget to go to Caesar's Palace and visit the Forum Shops.
6. Old Vegas "Downtown" has a light show every evening under the huge canope. It's fun and free.
7. The Cirque Du Soleil shows are all very pricey but good. Some of the other shows offered are more reasonable, if your interested.
8. Of course there are the shows in front of Treasure Island and the water/light show in front of the Bellagio nightly.
Hope this helps.