Teams in Miami and Atlanta are just asking for trouble. Not good sports towns. And, sorry, but Orlando isn't much better.
http://articles.orlandosentinel.com/2013-09-03/business/os-soccer-stadium-attendance-20130903_1_orlando-city-soccer-club-brett-lashbrook-usl-pro-championship
I know this is standard practice, but it's a big deal when you're trying to get an MLS team on the basis of local support.