While at Las Vegas, you may want to try to visit, aside from the casinos, the Arts Factory which features a collection of visual arts by artists, photographers, etc. The Bellagio Hotel has the Conservatory and Botanical Gardens which exhibit several rare species of plants and flowers, and the Gallery of Fine Art that shows different art pieces.
There is also the Bonnie Springs Old Nevada with an old western style motif, and the CCSN Planetarium and Observatory for the kids. You may also want to take a chopper ride to get a majestic view of the Grand Canyon in Arizona.