This last time I went, I went to the Shelby museum....and checked out all these different Mustangs.....it was neat. Its not an all day thing and is off the strip, so if you're into cars, its cool.
http://www.yelp.com/biz/shelby-museum-las-vegas for the address. Its right by the racetrack..you can sign up to race! That part is pricey and we didnt do it but it looked pretty cool..right on a REAL racetrack.