Don't listen to anyone that tells you to stay downtown; the amount that you'll pay in cab fares plus the opportunity cost of the inconvenience make several strip hotels a better option. You should stay at the Imperial Palace. Perfect location and absurdly cheap.
If you're going before Christmas, book the Winter Gold Special:
http://www.imperialpalace.com/stay.p...;contentid=420
After Christmas, book the Casino Gold Special:
http://www.imperialpalace.com/stay.p...;contentid=284
And definitely don't hit Vegas in the few days surrounding New Year's, because that will drive your room cost way up regardless of where you stay.