If I was casting a primetime "What's My Line," here goes.
Kathy Griffin, love her or hate her, was terrific in Brett's seat on the Game Show Marathon's Match Game. She's not afraid to be the foil. Caroline Rhea.
Shatner. Serious, but funny serious. Provided he could play WML better than Password. Or as someone else suggested, Ben Stein. Or heck, Wil Wheaten, since he played J. Keith's version, is younger, and has a funny outlook on the has-been celebrity thing.
Jessica Simpson. Because I like a little eye-candy, and she has to be pretty smart to play that dumb. Or Alyssa Milano, if she could play the game and doesn't pluck her eyebrows. Or Paula Abdul, who may or may not show up drunk. Or Sherry Shepherd, since "The View" gives her some fame and if the game falls apart with the others.
Then I'd have the fourth seat rotate. Craig Ferguson and Neil Patrick Harris, if CBS could cajole them. Adam Carrolla, Norm McDonald, David Spade. Ray Romano and Kevin James if you could get them.
Obviously, Anderson Cooper would be the perfect moderator, a modern-day John Daly, if he's not working too much. It would be nice to have a host with some currency who could attract decent mystery guests. Jeff Probst could be pretty good. I can see him messing with the panel.