I'd really like some more up-and-coming or "unknown" UCB performers doing characters. I basically mean CBB or Earwolf first-timers. Or even some well-known improvisers who haven't been on CBB.
I'd also love to hear Adam Scott in a non-F&P episode again. He's probably still the best "co-host" of CBB.
And some classic CBBer's who haven't been on for a while: Seth Morris, Natasha Leggero, Steve Agee, Jerry Minor, Rory Scovel, John Gemberling, Todd Barry, Tig Notaro, Adam Pally, THE SUPER EGO GUYS!!! (How have they only been on one episode? PFT needs to bring them along again)