I was somewhat dissappointed in the choice of Skyrim, especially after seeing such a bland and mundane treatment of Cyrodiil (although I have to admit, it looked really beautiful until boredom set in). Solstheim was my least favorite part of Morrowind and its official expansions, and I never even finished most of the quests there (including the expansion's MQ). My opinion of Bruma and the Jerall Mountains wasn't much better, as I'm just not a "cold weather" person. Hopefully, Bethesda can pull off a decent game, with challenging mechanics and unique and inventive things to do and experience in spite of the setting, or that modders can work miracles with it, otherwise I'll have to forget about buying TES V.
Taking the series to either Black Marsh, Elsweyr, or the Summerset Isles would have been much more interesting, in my opinion, and I'd have been happy with Hammerfell or Valenwood. Anything but Skyrim, or back to High Rock or Cyrodiil, and I wouldn't even want to re-visit Morrowind (which is probably not very interesting anymore, at least after the initial shock at the devastation and ash).