In Oblivion (It being the only other TES game I've played) the outdoors was mostly empty, with the occasional wolf or bandit etc. around. Just about every other quest involved going down into these annoying dark caves and castles. Which was not too scary, but I just get so exhausted by constantly being in dark places. I'm always on edge in an annoying way down there.
But in Fallout 3 and especially New Vegas it was a perfect mix. Mostly running around in the wilderness, and when you first go into a dark cave or vault it usually doesn't take too long. Just when I was getting annoying it would be finished, and I could go back out to the open and sunny wilderness. And the outdoors had lots of wildlife and quests and stuff to do. Loved it.
So obviously I'm hoping for the latter.