Carnival's 3 and 4 day cruises on the Fantasy-class vessels tend to have very active nightlife. There are several nightspots midship on the Promenade Deck. The piano bar is always a lot of fun, forward on the Atlantic Deck. Karaeoke takes place in the smaller theater at the stern on the Promenade Deck.

I just took a cruise on one of Fascination's sister ships, the Inspiration. it's an older ship, with fewer amenities than the newest megaliners, but there's still plenty to do. Fascination underwent a major refit in 2006 so she should be in pretty good shape. They added a minature golf course in that refit, I know for sure.