Blue lots seem to have the more frequent buses but that isn't as much the case as it used to be. Green and blue are the most crowded as they are the front lots to the entrances. My preference is Gold at the beginning of the lot to the right (near the road) right at the edge of the hill. I walk to the back of the lot once my car is parked and get on the bus at the last stop before it leaves (purple will also pick you up there), then get off at the first stop when the bus comes back to the lots.

The key thing regardless of which lot you're in is not to sit around and just wait when you get back to IAD. Look for the guy with the clipboard and radio and push him for info. When was the last time your color bus was there, is there one ON the way (not in the lot but on the road), etc. They can push to get the bus there sooner, but only if they are pushed. I've also been taken on other color buses b/c I've asked and they were told to do it, they never would've offered it.

Last - beware Purple has on again/off again shuttles b/c its still mostly considered an overflow lot. Make sure you ask clipboard-guy or a driver if they purple buses are running just in case - someone else will take you there, but you should be proactive.

Leave at least 30 minutes for the parking experience.

BTW - the best parking is valet, second best is garage b/c its walkable and the least desireable and still overpriced option is remote parking. I live about 15 miles from IAD and the tax roundtrip is less expensive than a 3 day parking stay in the garage since the last increase