L.L. BeanTysons Corner
L.L. Bean in Tysons Corner Center has a great selection of fly rods and flies. They have a good selection of budget to mid priced rods, reels, line, vests, and waders. The store has pretty much any accessory that you could need, from line snips to leader straighteners, to weights (lead to putty). There used to be a small selection of fly tying materials and hooks, but that seems to have disappeared. There are still a few fly tying vises, and some fly tying kits with enough materials to tie 30 or so of a certain fly. The fly fishing section is next to the street side of the second floor of the store.
The address again is:

L.L Bean (Tysons Corner)
1961 Chain Bridge Road
McLean, VA 22102