We did a museum trip one year and went to:
1. The Mob Museum
2. The Neon Musuem
3. Museum of Atomic Testing
The museums were GREAT - you could spend a lot of time at the Mob Museum, and although the Neon Museum is basically a walk around a lot with old un-lit signs, they do a fantastic job of telling the stories of the early hotels. In the Atomic Testing museum, they have a room that looks like a bomb shelter, and basically it's like you are there at Ground Zero when a bomb goes off with tremors, etc. I think we used a Groupon or something similar at the Atomic Testing museum, FYI.