As noted in a couple of other posts here, I do the 15 to 81 to 77 to 95 route and generally like it. I've been stuck on 95 heading south from Washington area a couple of times and it wasn't worth it. Truck traffic can be heavy on 81 and if there is an accident that can also get backed up for miles but it seems to be less of an issue than all of the slow downs on 95. Also a prettier route. You won't be the only one towing a big rig.