I drove there back in 2007, from Upper Michigan(Da U.P., eh). I took it slow(3 days out, 5 days there, 3 days back), and had the best time I've ever had at Nationals(YMMV, of course). If I were to go there again, I'd probably drive again, as the last 2 times I flew(Albuquerque and Las Vegas), and had miserable experiences with the airlines both times.
drillbit