Spunky Eclectic is fabulous -- she carries bulk natural fibers as well as a lot of hand-painted stuff. A good portion of my Christmas haul came from there. I just told my DH what kind of fibers I liked or wanted to try, and he chose the colors.
If you haven't tried BFL, I highly recommend it! The finished yarn is so soft and sproingy. Merino/Tencel is soooo nice too...a lot of places carry it...I know Paradise Fibers has the natural superwash M/T at a fantastic price. The Fold carries most of the Ashland Bay colors, and in their shop they carry a bunch of Blue Moon Fiber Arts handpainted M/T too. It's so droolworthy, and it's a dream to spin!
I've also really enjoyed spinning Cormo -- it's very soft, but the roving I got doesn't want to be very smooth...I think that the combed top might yield a smoother yarn. I got it from Wooly Booly Cormos.
I need to go start dinner but if I think of more I will come back later