I'd like to see a separate layover of wealth (maybe as a state, maybe per capita) added to that image. I'm betting it would explain in part why Florida and/or Texas appear better than one might expect. Just a hypothesis.
EDIT: Can't quite find the type of map I'm looking for but in the meantime I discovered that Texas and Florida are just behind California and New York for most millionaires (above 30 mill), so that's sorta along the lines of what I was implying.