A lot of secondary roads in central and southern VA are terrific. US Rt.15 south of Palmyra through the NC border is terrific. There's a little bit of everything. First 80 miles or so have lots of high speed sweepers. You're never slow for long because there's many places to pass on the left side. When it merges for about 15 miles with US Rt. 360, it's fairly straight, 2 lanes in each direction, and lots of visibility. Good for a high speed run (I set cruise control at a conservative 90-100mph last time).

As for Maryland, there's some good roads but the pavement tends to be poorer. In Potomac, Glen Rd. is a good drive and has some daunting blind corners where a sane person takes them at 20mph. You can take them at 60 in a BMW and fight with physics, but traffic often prevents you from doing so (there is no room for error.....you're between an enbankment and a guardrail over a stream). Out in western MoCo near Poolesville, there's lots of straights but the pavement is the limiting factor in speed and cornering. I'm not as familiar with north central MD, but I'm sure there's something there.

If y'all want a shot at off-roading, Green Ridge State Forest in Western MD has a couple ATV/off-road trails that are open to registered vehicles. I took the X3 there once over the summer; it's challenging enough to be fun on a BMW SAV, but I wouldn't do it if it was mud/wet. I used HDC about 15 times during my 7 mile drive!