I believe I was given an info sheet from when I took a class there, that said no go in the casino's. I checked the Nevada Laws and asked some people on another forum. The answer appears to be YES. If it is not posted. If you are made, they will ask you to leave, if you do it's over.
If you don't you will have Metro respond and you will be charged with trespassing, if you are lucky.
There is a recent incident where a West Point Grad Army Capt., was made in a store and a 911 call ,man with a gun, Officers responded and the young Capt. was killed as he left the store. Legal CCW with his girlfriend, non threatening and co-operative. It is still under investigation, you can Google it. I guess the short answer is Concealed is Concealed and as long as you are not spotted you should be fine. Hope this helps.