I just recently purchased the 8-15, it's a nice lens but it's pricey, and like you said it's not even close to an everyday lens. The 8-15 will leave you with a black circle at 8mm and will fill the frame at about 14mm. The Canon 15mm fishy used to be the fishy of choice, and I believe it covers the full frame of a full frame camera.
A good photograph is knowing where to stand.
Rule books are paper, they will not cushion a sudden meeting of stone and metal.
Ernest K. Gann-Fate is the Hunter.