I was able to skip most phases by passing speech checks so maybe I missed all the good stuff. Yeah, seemed underwhelming to me as well.
The first time I did the quest I passed all the speech checks too. The next time I purposely didn't. So I got to: 1) clean up the mess in the temple 2) rescue a goat from a giant- quite a task as a level 13 wielding mace/shield! 3) fight a hagraven who wants to "consummate your marriage"
The thing about this quest is that the title is ironic. You
don't remember last night, and that's when all the debauchery happened. Now you're retracing your steps and fixing your problems. Judging based on the amount of empty wine bottles in Morvunskar, you did have a pretty epic party with Sanguine. You just can't remember it!