Great comments, but I would also point out that the real party animal in the family is, apparently, Mrs. Columbo. In "Troubled Waters," when Columbo hears that the ship's Captain wants to see him, his immediate reaction is: "The Captain? To see me? It's not about my wife, is it? I mean... she likes to have a good time, sometimes she gets carried away..."
Apparently, it's a Columbo family trait - Columbo mentions as much to Mrs. Halperin in "A Friend in Deed", something about being drunk at a police function where our favorite detective runs into the eventually-to-be-murdered commissioner's wife.
I've always liked the sort of pool party he walks through for about ten seconds in Dead Weight.
Maybe it's really more like a casual get-together than a party, but whatever you call it.
There's the cast party in Dagger of the Mind, with its stereotyped English theatre people.
(I mean stereotyped in an entertaining way, like most of the characters in that episode.)