Just to give you a little "spinoff history" - every living major Cheers actor, with the exception of Kirstie Alley, has made a guest appearance on Frasier.

I think we'll see either Chandley & Monica (together) or Phoebe the most.

And for some reason.... I have a feeling that somewhere down the line, if Joey does become a success -- we'll see a wedding between Ross & Rachel on Joey.