With that decision made, I believe I'm going to make 3 or 4 different base classes, each of which would focus on a different aspect.
For example, something like an Avatar of Nature base class that would only have access to Animal, Elemental, and Fey bindings; as where something like The Vessel would focus on Angels, Archons, and Deathless. The 3rd class would focus on Demons, Devils, and Undead. The 4th would be your basic generalist class, that wouldn't be as strong as the other 3 more focused classes but would allow more flexibility in choosing your own bindings.
The PrC's would be open up alot of different paths and would give access to some of the more strange binds such as plants, giants, Jarrick's mad scientist (abberations and oozes), and the more 'specialized' routes such as focusing on Fey or whatnot.
So, with that decision out of the way, I can actually start working on the classes. Hopefully (if procrastination doesn't get in the way), I'll have one or more of the classes up and ready for critique in a couple days.