I've never ridden 606 (I drove is twice a week through most of the spring and summer) and I agree it's not ideal, but I often saw bikes on it they seemed to be doing ok. A short stretch on the W&OD, and the FC Parkway sidepath to Stingfellow avoids all the nonsense along route 50.
Bus or taxi out of the airport is a good idea.
Strongly recommend NOT taking US Bike 1. It will add a lot of miles to your trip to get to it, but it also sends you down (imo) some foolishly dangerous roads in southern Fairfax and northern Prince William. Going through Manassas instead of Woodbridge avoids the mess.
ps I'm convinced the main reason BR1 goes that way is to show off the Mount Vernon Trail. It is a beautiful ride, but since 2001, not being able to pass through Fort Belvoir to safer roads makes it a DEAD end.
Last edited by cc_rider; 10-06-11 at 10:22 AM.