Ordinarily, I would agree with Steven. However, if foliage is what you want to see, I wouldn't stay on the coast. It is hard to tell when the leaves will change anymore, but it used to be 10-13 days into October was a safe bet. Last year...I thought the foliage leaned towards brown, but there was a drought. Drought is no longer. You can usually check foliage forecasts in late September to know if NH or VT, north or south, would be best. Not knowing at this time, I suggest the following.
In October, the prime areas of Salem are beyond crazy. I suggest getting in and out, ASAP. Just see the memorial and leave. If you have an interest in Concord history, Battle Ground Park, etc. Stop around there for your first night. However, it's only about an hour from Salem. As you are not dealing with a time change, you might want to head further up Route 93 at a nothing stop. Then the Kangamangus Highway is lovely and could be done on your way to Franconia, round about. I also love Franconia and used to have a ski place there, so I'm partial. In Franconia, you could ride the ski lifts up to the top of Cannon Mountain for a view and/or head up to Brettonwoods and have lunch at the Washington Inn...make sure it is open. And/or head over to VT. As Stowe is so aligned with skiing, I don't go there. It's fake. LOL. As you love to drive and don't sound like you want to go to shop, etc. I'd suggest going up to Waitsfield, VT where the Appalachian Gap is. There is a beautiful view there, obviously. And, at Mad River Glen, you can also ride the ski lifts, if open, up to see the foliage. Check the timing of the App Gap bike race, because you'd have to put a hold on your trip up there just until it is finished, but the ski lifts would be open. If going to Waitsfield, I would drop Brettonwoods, but that's just me. Then on day three make your way back to Boston. However, that extra day does afford you a change of plans if you decide day two's drive is too much, which will be all day, but that seems what you want. I have done Waitsfield, VT through Warren, NH to 93 and back to south of Boston in a day, with several stops along the way and it was fine so you could do even more, IMO. I don't know how the cross over would be during foliage season so that is not necessarily your route. There was no cell service during part of that route. I was stopping to visit ancestors from Warren, NH, which was the reason for that route. Sounds like a fun trip.