Regarding diving deeper into Obj-C/OpenGL, you could also consider prototyping your ideas quickly using something like Quartz Composer. I don't know any specifics on whether it'd deal properly with a large data-set, but the learning curve is not steep at all and it might get you going quickly.
I've seen QC, poked at it a couple times, but never in depth. Any recommendations for resources?
Usually I'm struck by how unbelievably awesome the UI is, and how scores of similar attempts have been incomprehensibly awful. Meanwhile, Apple comes out with QC, a fast, elegant, simple version that goes almost totally unnoticed. Weird.
