That's pretty cool. It's impossible to include every feat and option in there, but it's pretty snazzy for getting the outline worked out.
Well, maybe I'll start talking about the not-so-secret parts of the plot I've been cooking up. I envision that for whatever reason brings everyone together (already a party, or in the same area, or individually recruited), an Ardent Dilettante (Planar Handbook) brings to you an interesting proposition: collect the DNA (or "magical essence," etc) of various creatures, small and great, meek and powerful, mundane and extra-planar. This could be blood, tears, bone, hair, semen, an egg, through whatever method you deem necessary to procure and preserve it. He (or she) is fairly knowledgeable and well-traveled, and is willing to be a kind of guide on this quest, should you need one.
In fact, if the party lacks some needed resource, I'm always willing to throw an NPC in to help. If everyone wants to make sorcerers, then I can include a meat shield or other heavily-armored thing, and vice-versa.