Another show with a lot of Columbo actors was "Burke's Law". It starred Gene Barry and Gary Conway, with regular appearances by Michael Fox, so that's a good start right there. Found one episode ("Who Killed Annie Foran?") that had Barry, Conway, John Cassavetes, Gena Rowlands, and Don Ameche.
Hi. Yesterday I watched the TV movie "Fireball Forward" (1972), with at least eight names related to "Columbo": Ben Gazzara (director in the series), Ricardo Montalban, Anne Francis, Dana Elcar, L.Q. Jones, Eddie Albert, Kenneth Tobey and Don Eitner. Regards