PART of what made the game great was the cultural identity of the time. So after reading some other suggestions regarding other locations outside the US, I would strongly disagree. It's part of what makes the game great and something I for one would like to see more of. Personally I thought Vegas was a massive disappointment. It felt like a bad DLC. Miles of boring desert and few surprises. It didn't have the same sense of adventure.
For my money I would like to see the west coast of the USA. San Fran to LA perhaps and in between and in-land. A map 4 times the size of F3. More underground too. A larger array of items to be found, useful too. Surprises that continue to be found even after many hours of gameplay. F3's Bobblehead collection was one example of the "Buried Treasure" syndrome that kept the excitement alive.
Wouldn't mind also being able to continue on being "The Lone Wanderer", which could mean some interesting story implications.
1. San Francisco and LA were already covered in either Fallout (LA) or Fallout 2 (SF), and would now undoubtedly be apart of the NCR. Most, if not all of California would be under NCR control by the time of New Vegas. Unless the NCR were to crumble after the final battle at Hoover Dam, which is unlikely since they're probably just going to have a change in governing, and the NCR name will still be around, I doubt we'll be seeing those places anytime soon.
2. As has already been stated several times by others, replaying the Lone Wanderer would kill any chance of being able to RP. If we were to play the Lone Wanderer again, that's all we could be, we couldn't be anything else. The back history of our character, would already be there, and we couldn't change that. It's best to do as New Vegas did with the Courier, and give us a blank slate that gives us hints and chances to fill in minor parts of our history, but not like Fallout 3 did, which was a bad move.
I was think more along the lines of landscape and cityscape I already knew about the kansas/missouri conflict
Kansas might not be that interesting of a state, but it still had plenty of landmarks and things, that could make it interesting. Plus, deadly tornados might be a cool thing to have?