No one has asked this and I don't think you mentioned it, but you ARE wearing PADDED bicycle shorts, aren't you?

If not, get thee to a LBS and buy a pair - that may make all the difference in the world to you. And if you already have them, well, never mind.

I went through 5 seats before I got one that was comfy. My bike shop was very good about letting me try seats till I got one that I liked (which they ordered in for me).