See, in Florida, the major urban population centers are spread out from each other. Also, Florida's shape makes it awkward to travel between, especially from the panhandle to South Florida. It can take over 4 hours to get from the Miami area up to the Orlando area.
The problem with Florida is that everything is on the perimeter. The panhandle is thicker with cities, and just south of that there is a ring - Orlando, West Palm, Ft. Lauderdale, Miami, Ft. Myers, Tampa, Gainesville, and back to Orlando - where the heaviest urban centers are. But within that ring is the rural area of small cities.
Having a high speed rail line could help the people living in those rural areas to access those major urban areas. Not only with this open up Florida's economy, as more people will have access to more types of shopping, it will also help Floridians get access to more job opportunities, as they can travel across the state easier.
Also, Florida has absolutely NO real public transportation system. This despite the fact that Florida has an incredibly large population of the elderly who could benefit from it since they may be too elderly or too disabled to drive on their own.
And please remember - Florida is NOT Yankee-land. If you do not have your own car, you are stuck wherever you are.
And speaking of other transportation projects in Florida, also keep in mind that the Port of Miami is the only place on the U.S.' East Coast that can be enlarged enough to allow new supercargo ships coming in from the Panama Canal to dock and unload their cargo. It's one of three possibilities, but the other two aren't able to. But Rick Scott is also preventing any spending on that because of budget cuts. Despite the fact that it affects not only the Florida economy adversely but also the economy of the rest of the U.S.
So when it comes to high speed rail, I don't think it should be built up in states that already have a dense transportation infrastructure, specifically in the Northeast. Rather, I really do think it should be built up in states without it, especially in the Southeast. By building it up and giving the people the option of using it, I think more will take advantage of it, especially in this recession where people can't afford cars but could afford train trips to get around.
So, in short, I don't think it makes much sense to spend money on transportation infrastructure in states that already have it - however, I think federal money should be spent on transportation infrastructure in states that currently lack it.