I can only base this on now,since I do not have the Vegas experience which many of you have so:
New York New York: for the ambiance and the great deli we go to before we start our day on the strip
Orleans:Love playing poker there.Good games and many regulars.Your hourly may not be great,but at least you know what you are up against most of the time.
Red Rock:One of the nicest poker rooms around in my opinion.
Venetian:Cause when you aren't playing poker,it is a great atmosphere when you are with your wife AND...if you happen the be there during the AVI awards.......WOWEE!!
Hard Rock:Give that place a poker room and I would never leave there.