I got the 14-18 varitooth bi-metal blade for my 64 1/2" band saw. I don't bother changing blades any more. I use it to cut everything - wood, stabilized wood, carbon steel, stainless steel, brass... pins, sheet, pipe, .... I too was agonizing over the size. I took Mike Hull's suggestion, but got the varitooth. Will probably just get a 14 tooth next time.
Oh yeah, I got mine from MSCDIRECT.COM.
steve