Additional to vegasrocks: This map of the Las Vegas Strip (see attachment) is really handy to determine where each hotel is located in comparison with the others. It is not 100% up-to-date (everything changes so quick in Vegas!), but i find it still very useful.
And about the rooms: if they are clean or not, maybe more depends on the cleaning person that particular day, than on the hotel's cleaning policy? Because when i check hotel reviews, i always see completely oposite reviews about the exact same hotel. Of course, it should also not depend on luck

if your room is clean or not

!! But i can imagine that when your friends would have serious complaints about their room, that the hotel management will do their best to make them happy again (maybe even a free upgrade to a better room?!).
And, ones your friends make their decision about which hotel etc, will you let us know about it? Then we can taste it a little bit and day-dream away!
LAS VEGAS STRIP MAP (attachment):