I went over to Towners bike shop over lunch yesterday and picked up a new bolt for my seat-post collar. It wasn't long enough, but it was working. As a precaution, I went out and picked up another one last evening ($6, I can handle it). I put it on the bike when I got home, adjusted everything, and voila, my seat didn't fall down. In addition, it no longer squeaks. I'm proud of myself for figuring out what the problem was, and fixing it, though fixing it was almost entirely by accident, since the bolt wasn't supposed to shear off. Anyway, 75 miles on the bike and going strong... now if only I can get 100 miles in one ride... granted, it'll need to be flatter, and I'll need someplace to stop for water, etc, but I think it's doable.