Mob museum or neon museum. Might need to make prior arrangements for neon...it sometimes could get booked up(especially at night) I also recommend Triple George Grill. We eat there and at Bootlegger's(Italian out toward South Point Hotel/casino) every time we go to convention.
If you like collecting chips or other gaming memorabilia ......Spinetti's has a entire store based on gaming. Also Lost Vegas Antique's (next to Pawn Star's)had many artifacts. Even if you don't plan on buying... It's cool to look!