I would recommend you get the FAA PPL at any of the good schools who teach also for the JAR PPL. That way you will have a standalone US certificate to add the IR to later,
Dont forget you can add an FAA IR to your US licence based on foreign licence anyway so if you already have your JAA PPL dont get talked into taking an extra PPL or paying for 2 PPLs when you dont strictly need to.
You can go onto do your FAA CPL without ever taking the FAA PPL in this manner.
Julian