My favorite is Columbo crashing the Undertaker's Award dinner in Ashes to Ashes and the one I would like to attend is the Restaraunt Writer's dinner in Murder Under Glass, if anything, just to sample the food.

Haha! Yeah, those were great scenes. I've always wondered what they did with all that food from the Restaurant Writer's dinner. Did the cast, crew and stand-ins all eat it?

Some people would see the ones in "A Stitch In Crime" and "Suitable For Framing" and just see a lot of overdone late ' 60s-early ' 70s people.
But I think that's kind of the point, because those two parties are little send-ups of that kind of thing. Except that they're pretty low-key send-ups (especially the "Stitch In Crime" one). Either way, they're entertaining.

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.

Good about in A Friend In Deed when Columbo admits to Mrs. halperin he was drunk at the Christmas party.

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.)

A Deadly State of Mind. When he’s sitting with the doctors and explaining the case he’s working on.

I can't help thinking that a character played by Danny Wells could make any party a good one to attend.