Alright, I've lived in Vermont for a long, long time, and been hitching around a bit for the last 3 or 4 years.
In my experience VT is a great state to thumb it, here's why:
1. If there's any laws about hitching, they are not enforced, I've hitched cars in front and behind cops and wasn't bothered.
2. People are really friendly and willing to pick up hitchers, and occasionally give them a place to stay and if not you're never ever far from some woods to camp out in.
3. It is a beautiful state, except in February when it is colder than a witch's tit. If you are hitching into Vermont in February all the locals will give you strange looks.
Some good routes to take in VT:
* I thumbed north up Route 100 a little while ago, it's a really nice route, it goes right through the mountains. Towards the northern end, just before the town of Warren and Sugarbush Resort, there is a really nice waterfall, called Warren Falls, it's right on Route 100 and I recommend you scope it.
* I'd go into rural Vermont for at least a little while, and if you want rural, go to the northeast. There's nothing really to do but hike or wander in the woods, but if you need to chill out, it's a good spot. Once you get to the back roads cars are MUCH more likly to pick you up, but on a lot of roads, cars don't pass very often, generally if you stick to paved 2 lane roads you should be okay. Once you go to dirt, you can wait for hours before a car goes by.