I shoot a lot of college basketball and switch between 50mm and 100mm lenses. (I'd use a 35mm lens, too, if it didn't seriously slow the frame rate.) I tried a 135mm lens, but that's too much magnification for basketball.
So why doesn't Canon, or any other lens manufacturer, make a 35-100mm f2 (or even f2.8) lens? I would buy one in a second if it was available for a reasonable price.