I think my favorite place in the game is the Glowing Sea
It's one of the most dangerous places (which isn't really saying much, but still) and there's all sorts of weird and creepy stuff to explore, like the Sentinel Site and the crashed airplanes
I've noticed one big thing about "dungeons" in Fallout 4 though, and that's that they always have some sort of chest at the end but it never contains anything I actually want, just like...a handful of caps, ammo I don't really need, and some armor pieces that are stufftier than the stuff I crafted 10 levels ago
I guess it's for people who didn't take any of the crafting perks and need to rely on loot, but I don't know why anyone would want to do that? Maybe crafting is overpowered now that I think of it