DCL does go to other destinations. Alaska, California coast, Canadian coast, northern Europe, Norwegians fjords, British Isles, Mediterranean, Mexico Panama Canal, Transatlantic, sometimes Hawaii.
My wife and I have so far only cruised on DCL, but recently have started talking about exploring other lines. She does have one condition. She does not want to be in any port at the same time as one of the Disney ships, so she won't see it and be disappointed that we are not traveling with the Mouse. Also has no interest in going on one of the mega ship floating cities. We prefer the original, snaller ships on Disney.
THIS IS ME! We're jumping ship and trying the NCL Escape in October (we're considering it to be our "training wheels" cruise to see if we can enjoy ourselves without constantly comparing it to DCL) and I don't want to see DCL anywhere! I'd be too sad (but still hoping the our new experience is great!).
Our kids grew up on DCL (and we've done several adult only cruises on it as well) but we're priced out and ready to try other lines. The "babies" in our groups are turning 21 and wanted to celebrate on DCL, but it's not going to happen.