Just found this thread...some great information here!
I was surprised that none of the "East Coasters" mentioned the Northern Neck of Virginia (the peninsula between the Potomac and Rappahannock Rivers, and Chesapeake Bay). There is a broad swath of blue/dark green (Bortle class 3) dark sky conditions stretching from northeastern Northumberland County (Smith Point) southwestward into Lancaster County and the Rappahannock. This area is an hour from Richmond, two hours from Norfolk, and 2 1/2 hours from DC.
I've owned property in that zone for several years now, and the seeing is superb!
I've observed across the Potomac from the Northern Neck. This was at Point Lookout State Park at the south end of St. Mary's County. The sky there is blue/green. Too bad there is no good area to set up at the south end. It is ruined by a historic lighthouse with outdoor lights on all night. Best I've seen is a camping site that can be rented at a lake.
Sometimes I've thought about going to the Northern Neck to check out that area. I can see from the light pollution maps that it should be pretty dark. I've never heard about any active astronomers there until now. I'll have to see if there are opportunities for observing at the parks and other locales on the Northern Neck. Renting a cabin with access to dark skies would be nice.
My usual observing site is in Tuckahoe State Park on the Eastern Shore. Not the darkest at yellow/green, but it is the closest for me. That does count for something.
We have friends that have a house in this area right on the Potomac, just before it dumps into the Bay. It's right across from the Point Lookout SP that Mike mentioned. The skies there are very nice and I look forward to viewing anytime we're invited out there. Our friends get a kick out of viewing too.