We are not into the loud clubs, but would love to go out and enjoy some jazz and blues and maybe dance a bit. There seems to be a ton of wild clubs - anyone know of something a little more for the over 40 set.

Depending on who's playing -- The Voodoo Lounge atop Rio.

A couple of places they we enjoy are Napoleon's at Paris and Terrazzo at Caesars Palace. We try to catch a set by Ghalib Ghallab at Terrazzo every trip. Great jazz! We've had nice jazz at Napoleon's as well, but last Valintines Day, the combo was really bad, lots of covers of old 70's pop music, we left after one glass of wine.
Both of these clubs are laid back and have comfortable seating and a sound level that allows for conversation,
Enjoy,

Unfortunately, Terrazza at Caesar's is no more. It closed and is being re-opened (or has been re-opened) as Rao. I am not sure if they will continue to have live music.

I belong to the over 40 set. My DW and I always enjoy the dueling piano lounge at NYNY. There is a similar one at Harrahs but have not been there.

No dancing but great fun...can be tough to get a seat unless you are there near opening. Actually leaning on the wall or something is not so bad.