I'd like it to be either in a mountianous area (like the Appalacan Mts) or in a marsh-like setting (Florida everglades). However what I think is that it'll be in one of 2 locations.
The Commonwealth. it was Mentioned in Both Fallout 3 & in passing in FNV. Or...
Navaro. it was a part of Ed-Es background & if what is/was said by both him & his Lonesome Road counterpart are true then there are Enclave remnants there.
the applacians, them old worn out hills? how about a real mans mountains like the rockies or the sierras? jk. point lookout was a nice kinda marsh like place, too bad it froze on me so much i couldnt enjoy it.