You may want to try http://www.ian.com/
I never had much luck with them, but there’s no wait time or approval period after signing up, and you can promote pretty much any hotel. The one thing they seriously lack is banners, so a text-based approach would be better.
Commissions are probably lower than what you’d get from a more specific program (such as Wynn or MGM), but it still might be worth looking into.