Longest - either the 7 months I did on Royal Viking or the 7 months I did on Holland America as a crewmember.
Shortest - overnight in the Port of Long Beach (never sailed).
Longest "regular" cruise is probably about 17 days on a Crystal Trans-vanel, only three ports of call and I never got bored.
I have only done 1 regular weekender cruise, and it was a music cruise. "Pretty wild shtuff" as Johnny Carson used to say.