The chances are, you already planned it since this was asked months ago. but future readers could benefit from this post...
Is it important for you to stay on the strip? or you open to staying away from the strip, or even in suburbs?
What kinds of things do you plan on doing there? get the priorities straight.
This site : http://www.findhotelsin.net compares hotels and prices from all reservation websites. Personally, I've stayed at the El Cortez and Vegas Club. both are downtown, I chose them because of affordability.