Florida would be great, but as several have mentioned, Disney lawyers would lay siege to anyone even hinting at their property 
As a New Orleans native, I can see some nice aspects to that - you've got your generic city stuff like any FO game, maybe have the Superdome as a major hub/city/whatever, and then throw in all the non-desert stuff several have mentioned (swamps, bayous, etc., along with the corresponding wildlife). Throw in cool stuff like oil rigs out in the Gulf as a nod to the ending of FO 2, maybe. And historically, political corruption is so bad in La. that it would make the contrast between Caesar's Legion and the NCR look like a girl scout picnic - there would be no good guys, only varying degrees of bad
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And while the FO universe has been strongly averse to vehicles, one could argue that boats are a different matter, and to incorporate fishing, mutated sea life, travelling to hidden islands, etc. - that might be worthwhile. Have the Sons of Jean Lafitte as a waterborne band of raider-pirates, etc.
As a New Orleans native, I can see some nice aspects to that - you've got your generic city stuff like any FO game, maybe have the Superdome as a major hub/city/whatever, and then throw in all the non-desert stuff several have mentioned (swamps, bayous, etc., along with the corresponding wildlife). Throw in cool stuff like oil rigs out in the Gulf as a nod to the ending of FO 2, maybe. And historically, political corruption is so bad in La. that it would make the contrast between Caesar's Legion and the NCR look like a girl scout picnic - there would be no good guys, only varying degrees of bad
(edit)
And while the FO universe has been strongly averse to vehicles, one could argue that boats are a different matter, and to incorporate fishing, mutated sea life, travelling to hidden islands, etc. - that might be worthwhile. Have the Sons of Jean Lafitte as a waterborne band of raider-pirates, etc.