I've traveled it many times
making time north and south Mark. It and I95 are the two main ways to make time north and south through VA. I 95 stays east and is one of the busiest, fastest, traffic laden, NASCAR-like freeways in the country and can be bumper to bumper from No VA to Richmond on work days. Avoid it like the plague. I-81 is the western bending southern route, all 2-lane (each way) and often busy (and full of trucks), but a much better ride than 195. Rolling hills the whole way, and plenty of cops too. Better to pick a speed that will not get you in trouble and sit back and put in the hours. It goes from pretty open to pretty busy, but usually never backed up and keeps moving. Plenty of gas and motels all the way down, and easy to see from the freeway (with signs listing what is available at the next exit). My advice for overnight (as always) would be to choose a place away from the main population centers where traffic and prices and bad humans can be increased. Pass through a big population center,
then get a motel. The I81 freeway speeds are 55, 60, (lots of) 65, and 70, so the lower it is, the bigger the population area you are in.
If you want to make the ride South through VA better (and more time consuming) you can get off 181 in Front Royal VA and get on the Skyline Drive south ($15)(35mph) (the top two LONG exits of Blue Ridge Parkway) (which transitions to Blue ridge parkway, same road), or skip that and save about 2 hours time, and get off I81 in Staunton VA, and run over east a short ways to Waynesboro and get on the top of Blue Ridge Parkway south (45mph) (mile marker 1). If you do this, you want to do some homework on good places to get off for gas, before the ride (you rarely can see gas stations from the BRP, and they can be right around the corner, or 20-30 miles away) Here's the site:
http://www.blueridgeparkway.org/v.php?pg=50But the BRP eventually heads more straight south, wereas I81 keeps bending west, toward (and into) Knoxville TN.
I have done the BRP up and down many times, and if you keep at it and only take short gas and food breaks, you only add a couple hours to your I81 faster ride, but down at the bottom of VA, you'd lose more time having to run back west to Knoxville (and the best freeway west off BRP down there is I77 W, back over to I81 S).
Temps should not be bad, cool mornings, but can jump up
any time in spring. You absolutely want rain gear. I don't think I've ever run up and down I81 down to TN or NC without getting rained on hard for some of the ride up or down, or both.
And if it's raining, I keep to I81 and not the BRP, if I'm trying to make time. BRP in the rain gets dark and muddy and foggy and slow and the deer play in the rain. Nice and sunny though, it is one of the nicest rides in the country.
I've often played it by ear, and if it's nice, take PRP down and I81 back. But if raining I81 down and BRP back (unless it's still raining).
