DO NOT "surprise" your wife with something like this.  You say you've "talked" about it--but if you don't know what she would or would not be "cool with", you haven't talked about it enough.

Well over half the TER-listed Vegas providers are willing (sometimes even eager) to do couples.  However, nearly all of them will make it a firm requirement that the wife (or gf, whatever) is the one who makes the contact, fills out the screening form, etc.  Most will also want to have a brief phone chat with the wife as well.

The last thing a provider wants to do is be a "surprise" for the female half of the couple.  I'm sure that every couple-friendly provider has had nightmares about that scene in "9 1/2 Weeks" where Kim Basinger freaks out when Mickey Rourke brings another girl into the picture as a "surprise".

Save yourself from a potentially awful experience.  Make sure that your wife is willing to move beyond "talking about it", and make sure you have ground rules about what everyone is "cool with".

Stay safe.  Plan safe.  Play safe.  Play smart.  When you've done all that, enjoy, m'man!