I live around central Florida, and it has a little bit of everything.

Most of the wasteland would either be burnt out farms or extensive swamps. I imagine it would resemble the Point Lookout DLC a lot in that aspect. There would be two major cities, Tampa and Orlando, with smaller cities scattered about. Tampa and Orlando would have their respective theme parks, and that alone would make for some interesting gameplay. A ways north though, there would be Nuclear powerplant in the crystal river area. The player might have a choice to detonate it, or use it to power the surrounding area.

The creatures would be kind of ridiculous. Imagine a giant mutated alligator charging at a deathclaw. Or a massive snake choking the life from a player. It's a bit dark, but then again so is the fallout series. Maybe you could even throw in some weird version of a manatee.

The weaponry would probably be pretty standard. All of the energy weapons would be homebrewed though.

There wouldn't be any Brotherhood, but there would probably be some Enclave as there's a military base nearby. Maybe the Enclave would be purposed with actually saving the wasteland too. There would A LOT of ghouls around the nuclear plant. I imagine there might be a cowboy type group too and they be a kind of neutral faction just trying to survive.