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.