Kalen --
I have a few thoughts:
1. Royal New Kent will be closer to a three hour drive (assuming no traffic problems, which is not a safe assumption to make) from Landsdowne.
2. A course not yet mentioned on this thread is Shenandoah Valley Golf Club in Front Royal. Walkable, cheaper than any other course mentioned in this thread ($15 to walk in December), classic, rolling hill, walkable layout. 27 holes. the older 18 has smallish greens, the newer 9 has larger ones. Almost no forced carries or water hazards, some blind shots, usually kept in nice condition. Some very interesting holes and I think it's the best value in the area.
http://www.svgcgolf.com/golf.html3. Of the CCFAD courses in the area, I think Laurel Hill and Westfields are the best. Laurel Hill is actually a muni trying to be a CCFAD; I personally think it has several outstanding holes and no bad ones.
4. Raspberry Falls has some nice holes, and it is close to where you're staying, but it's a couple of notches below Laurel Hill and Westfields. Also good in the Frederick, MD area are Whiskey Creek and Musket Ridge. Virginia National is the kind of course some people hate, but it is a pretty unique layout; but I'd call first as they may be closed for the season.
5. I second the rec for Twin Lakes -- it's the muni where I keep my handicap. Two 18-hole layouts: the newer Oaks is more challenging and interesting, and plays a little tighter; the Lakes is more open but the greens are far less interesting. Conditioning can be an issue, but the price is right and they always allow walking (most CCFADs in the DC area don't allow walking on a weekend morning, though they might in December).