I have the 10-22 for landscapes, and the 50mm 1.8 for low-light. Crop camera. I want the longer lens for Alaskan wildlife (whales, seals, bear) and climbers in Yosemtie (secondary). Also for some sports photography (whitewater kayaking).
I was thinking about the Canon 200mm L 2.8, and my budget is around $800-$900. I would like the 70-200 f4, but I believe it will be too slow. The longer primes are out of my price range, and I have heard the longer zooms have mediocre image quality (anyone care to differ?). That leaves me with the 200mm 2.8 for good quality at a good price, but I don't want to buy it if I'll find out it's too short for my intended use.