http://www.vegas.com/shows/
Search for shows between the dates we're staying and see if anything comes up you want to go to Most good shows are going to be $50+ but there are some cheaper comedy shows and such that people might be interested in, and we may be able to get coupons for shows once we arrive.
Please be advised that most "rewards clubs" that you sign up for will also offer free perks such as free slot play, show ticket discounts and food discounts. Last time we signed up for some free slot play ($10 or $20 i don't remember, it was at the Ellis Island) that let us cash out the money and keep it instantly. We might want to pick shows once we arrive, but that search will give you a good idea of what's available!