Apparently, Dick tried to raid the entire cast of Fridays to make them the Season 7 cast of SNL. In particular, he really wanted Melanie Chartoff in particular. I've heard he also tried to get the entire cast of SCTV to become the Season 7 cast of SNL (and actually got Catherine O'Hara to jump before she jumped back after being annoyed/scared by Michael O'Donoghue's antics).
It really is moderately surprising that Michael Richards was never on SNL. It seems like he'd have been tailor made to be an Ebersol era castmember plus he was the one Seinfeld castmember to not host.