No real placed to "open it up" but there are some fair driving roads.

Brooke rd from the Brooke VRE station to Deacon Rd, short but worth the trip
http://maps.google.com/maps?f=d&hl=e...,0.110893&z=13

River Rd. to Spotsy Furnace Rd. to Eleys Ford Rd. to Lignum. About 22 miles, mostly 45MPH but lots of turns. Not like the Blue Ridge PKWY though =)
http://maps.google.com/maps?f=d&hl=e...,0.443573&z=11

There is also Mt. View Rd. Was beter before the construction for the airport. I used to have a client up there, and looked foward to site visits =)
http://maps.google.com/maps?f=d&hl=e...6&ie=UTF8&z=12

All will require that you avoid the traffic, or egg timers as my wife calls them (a reference to Christmas Vacation).