To be honest, don't go with these big JAR schools for hours building only, they don't care too much about hirers. I went with Sunstate Aviation in Kissimmee last year, and they were fantastic. They gave me a plane for a week and I could do with it as I pleased so i did the big tour of Florida, gained 25 hours and had a great time. Was more of a holiday experience but it also added to the 100 hrs P1. They weren't the cheapest but they were fantastic and helpful in every way.
What you need to do is navigate without GPS, as this is entirely legal in the US for primary navigation, keep within the tolerances of the CPL in terms of height keeping and heading and fly the long way round to places keeping out of controlled airspace. ATC were so helpful they found it odd that I wanted to route around the class B instead of through it! Enjoy it and remember you don't have to go to a JAR school for hours building, as you have to have a US licence based on your UK licence to fly in the US anyway.
Choice is yours but it won't matter a bean who you hours build with in the US. As long as you save money. Florida is a boring place to fly though. Don't overfly Lake Okeechobee either, especially in a single engine, I didn't realise at the time it has one of the highest concentration of gators in FL. Had I had an engine failure I'd have been lunch!