It would be great for Fallout 4, like the recent rumors, to take place in Boston. Its main city would be the Commonwealth, which is where Zimmer and Harkness from Fallout 3 are from. Also, Dr. Madison Lee went over there between the events of Fallout 3 and Broken Steel. I think the locations would be fun to explore like Freedom Trail, Fenway Park, the Museum of Science and more. Also, there's lots of American history to see in there. Maybe even you could find Plymouth Rock. There are also many DLC opportunities. Maybe even some British remnants could go there because they read history and thought to take back America.
I'm thinking of something either very new or taken from the past. Maybe your character is born in a vault, raised in the wasteland or we could take a whole new farfetched path. Maybe something along the lines of cryogenic freezing. Either you're a soldier who is buried in snow on the Anchorage Cliffs or maybe you somehow got on the Mothership Zeta and was accidently set free by the Lone Wanderer but both of those are farfetched. Even more out there with the Anchorage plot is that you're an ancestor of either the Lone Wander(Fallout 3) or the Vault Dweller(Fallout) and Chosen One(Fallout 2). Anyways if you're raised in the wasteland, I'm thinking you're on a raiding mision as a captive who is feeling amnesia due to tragedy and you're saved by a major faction either the NCR, Brotherhood of Steel, or maybe even the Enclave is a good guy on here. But you're picked up and maybe you're with the faction and you get seperated after things go wrong in a meeting with another major faction either the said factions before or new ones such as the Commonwealth Military Police or the Boston Coastal Guard. So you end up in the Commonwealth Wasteland, trying to make your way to some major Military base to find out about your past. Another way you can go is that you're on the Anchorage Cliffs as a pre-war soilder and you get caught in a landslide after finding out some information changing everything about like everything and you are dug out by the Enclave or some other post-war military faction. The faction seems to be nice but you find out their using you and escape. Either way, the Institute should play a big part.
I'm thinking of a more realistic Fallout. Maybe without sufficient armor, you are more easily injured with lethal headshots and broken bones or something. Also a bigger endgame boss than just a man. Maybe someone like Frank Horrigan. Also maybe you can buy a tesla powered motorcycle after the main quest. Oh, and there has to be something like Broken Steel that extends the game. They should also use the Skyrim system where you can level up skills by yourself and you can get the perfect player. Also the level cap should at first be 50 but then the dlc's should make it 80 more. New weapons would be great like Hockey Sticks or paint ball guns and maybe even a historical cannon. That's some ideas I have.
I was talking about DLCs earlier and I was thinking there should be 6. 1. A Roanoke Island or maybe somehow a Hawaii add-on. 2. A New York add-on. 3. One that gets you into a military vault like in Anchorage maybe tied in with an Alien underground military base where you go through it and at the end discover all these prototypes. 4. A British add-on with the British remnants where they can take you on a ship to England because they think you're an ambassador or you just ask them. 5. A extention of the original game like Broken Steel. 6. A vertibird to Hollywood.