I live in Warrenton - about 30 miles from the Skyline Drive - and spend a lot of time up in the Shenandoah National Park and drive a lot on the SD (haven't biked it yet, believe it or not). The weather this weekend is supposed to be beautiful and the leaves will probably be at or near peak color up there. The cyclists, motorcyclists, and cars will be up there in droves. There is likely to be a long line to get into the Park and traffic jams (literally) and lots and lots of people entering and exiting the overlooks. Be careful!