Heres a list of places I have been to that I know:
Strip (south to North)
Exclibur
Luxor
MGM (I believe you may need key but its always so busy a provider can hitch a ride I have never used a key at MGM)
New York New York
Planet Holywood
Cosmopolitan (same as MGM Im sure you need room key but its SO hectic the elevator is always full of people happy to press the button for you)
Mandarin Oriental (but it has a sky lobby - you have to enter via one elevator which ONLy goes up to a highrise Lobby floor and go to the lobby desk and is NOT discreet at all!!! then take a SECOND elevator to the actual floor you want UGH)
Caesars
Paris
BAllys
Quad
Mirage
Circus Circus
STratorphere
(basically most of them)
Offstrip:
Rio
Silver 7's
Any location in the Station Hotel chain
Golden Nugget Including Rush Tower (best towntown)
4 Queens
The D
There may be more these are just the ones Ive been too.
NB: I have NEVER needed a keycard in Vegas in past 9 months
