In the Northern Virginia area I would recommend a stop by Merrifield Garden Center. I have not been to the Merrifield location, but the Fair Oaks one is not too far out of the way. It has a large selection or shrubs, tree and perennials along with a nice display garden. The prices tend to be rather high, but in line for the area, quality and size.

- Brent

Here is a link that might be useful: Merrifield Garden Center

Bluemont nursery in Ashburn, Virginia and Holly, Woods and Vine in Alexandria, VA.

Here's a second to Merrifield Garden Center. The Fair Oaks location is better (better selection of perennials for shade, and sun, plus more shrubs) than the Merrifield one, but the staff is friendly and helpful at both.

Suz

Sandy's Plants in Mechanicsville outside of Richmond.

Just down from Merrifield Nursery on rt 29 (an overly expensive nursery)is Betty's Azalea Ranch, looks like tackville from the road but has great selection.

Sadly, Windy Hill in Aldie was the place for perennials but is closed down this year. I still like to make my way down rt 50 though, there's South Riding, Green Star and (puke) Meadow Farms for an occasional gem lost in the walmart like selection.

I'll second the Sandy's nomination. They're not too far off 295 east of Richmond. It is mostly wholesale, so don't expect a lot of hand-holding. Their retail prices are average.

You'll want a hat and some water with you- you'll be out there a while.

Here is a link that might be useful: Sandy's Plants

Colesville Nursery is just north of Richmond in the Ashland area. They have a website and directions. Like Sandy's they're mostly wholesale but sell retail, also.
From Richmond:

Take I-95 north to the Ashland exit (92B). Go 1/2 mile to Route 1 (the 3rd stoplight) and turn right. Proceed north about 1.2 miles to Jamestown Road and turn right. After crossing over I-95 you will see Colesville Nursery signs and will take a left onto Nursery Road (our driveway).