This is the final list of hotel security I am going to post.   I have changed the categories somewhat changing the category of security at particularly times to special mentions.  There is a short list where I have not received any information.  Someone can reply to this post to five that information.

I hope that the list is helpful.  

Ol_Desperado Provided Security:
Days Inn.

Keys Required and/or Checked at All Times:
Aria
Bellagio 
Cosmopolitan
Cromwell 
D
Encore
Excaliber
Four Seasons 
Luxor
Mandarin Oriental 
Nobu Tower
Orleans 
Palazzo
Palms 
Red Rock 
SLS
Sunset Station
Vdara
Venetian
Wynn Towers

Special Mentions:
Caesar's Palace - Inconsistent information - Some indicate security always, some starting at 10 pm, some indicate none.  I did receive information that one or more employees of Caesar's are hostile to providers.
Hard Rock Hotel - Keys required for the elevators, but not for the lower six floors.
Mandalay Bay - Inconsistent information - Sometimes security sometimes not.
Mirage - Security after 10.
Palace Station - Inconsistent information - Key Card required versus not.
South Point  - Inconsistent information - Security at all times, but not consistent in checking cards versus security after 10.
Treasure Island - Security at random times.

No Security:
Artisan
Bally’s
California
Circus Circus
Embassy Suites
Flamingo
Golden Nugget 
Harrah’s
Hooters
Hooters
LVH 
M Resort
MGM Grand 
Monte Carlo
NYNY
Paris
Planet Hollywood
Rio 
Rivera
Stratosphere
The Quad
Trump 
Tuscancy

No Information Received:
Green Valley Ranch 
Tropicana 
Sun Coast 
Delano 
Aliante 
Silverton