It seems a shame to head inland without seeing a bit of the coast, but I"m not sure what to suggest with your limited time.

~Liz

If you're going during foliage season, it's very late to be making reservations for this year. I would get on that right away, once you decide where you want to go.

Do a foodie tour of Portland while you are there. It's a lot of walking in the Old Port Area. You can have a late lunch afterward. Suggest trying the french fries at Duckfat. Don't miss MDI ice cream on Extension St. It's not on the tour. Has very unusual flavors. Go when it's not busy. Ask for samples. Then get the sampler dish. I didn't care for the flavors with heat (wasabi chocolate) so just a taste was enough.

Foliage varies. If it's the first week or two, color should be good in Norwich. Local roads are actually better than interstates. Avoid southbound interstates on Sunday afternoon; northbound on Friday afternoons. Have a good map of each state. The most detailed maps are the state atlas and gazetteer published by Delorme. They are oversize and show most roads. There are state roads that usually parallel interstates that are a good alternative when the interstate is bogging down.

Probably eat at Simon Pierce in Quechee VT while you are in the Norwich area. You might investigate posts on chowhound.com /northern New England for some recommendations. Pizza on Earth in Charlotte VT is only open certain days since it's a little pizza place on a farm in rural VT. Good pizza and unique setting.

Read "The Town That Food Saved" by Ben Hewitt. It's about Hardwick VT and will give you some idea of active, successful food businesses in a rural area.

The New England states have developed food maps/trails to find wineries, farms where cheese is made, homemade ice cream places. I would recommend visiting a good apple orchard that grows a variety of apples. Should you decide to go back to the coast - Norwich via I89 will take you to Concord NH. Gould Hill Orchard is not far off I89 just west of Concord. Then I93N to I393E to Rt 4 etc to Portsmouth NH. You could take a detour for a visit to Flag Hill Winery and Distillery. (They make Gen John Stark vodka.)

Norwich Vt is an ideal base to explore both NH and VT. This area is quite rural and unspoiled. You are close to Hanover NH which has a good selection of restaurants, plus a nice museum, and a very picturesque college campus. On the Vermont side, you are just a quick hop to Woodstock Vermont, a popular, somewhat upscale Vermont village. Just outside the village is Billings Farm & Museum. You can take a hike up Mt Tom right in Woodstock. For a more energetic hike, Mt Cardigan NH is less than an hour from Norwich, as is Mt Ascutney Vt. Close by Ascutney is the Windsor/Cornish covered bridge, the longest in the USA, and the tranquil and scenic St Gaudens National Historic site.
Burlington VT is a great little city, and if you want to explore Montreal (one of my favorite cities anywhere), it's an easy hour drive from Burlington.

You have two very general routes to get there.

You can take the Kankamaugus Highway across the middle of New Hampshire Google maps will get you there from Portland -- disable the interstate highways button for scenic routes. Or you can go through the Presidential Range of the White Mountains, much larger and steeper. through Pinkham or Crawford Notch or, with a little backtracking, both. There may be snow on the mountain tops. You could drive to the top of Mt Washington on the Auto Road from Pinkham Notch (a bit "airy" in places) or take the Cog Railway, the first in the world and still steam, from Bretton Woods. At Cannon Mountain (next Notch over) you can take a lift to the top of the ski area for views.

Given where you need to be on night three, you will probably want to do some back tracking to see NH and Maine - otherwise you are covering most of the area in the first two days and have the last four for just Vermont. But road trips are about back driving so I would take one route from Portland to Norwich, do your class (assuming you can't change the date of this), then take a different route back across NH to Maine for a couple days, then a third route back across to NH to Vermont. Yes, there are at least three different route across NH, you will see different things for example: norther route- white mountains, middle route - lakes, southern route - well that's pretty too. In Maine you could do either the Portland to Camden stretch, or Portland to Porstmouth NH stretch - or both, a day for each.

This is if you want to see some varied scenery that includes mountains, lakes, coast, cute towns, etc. You could spend the whole second half of your week in Vermont, but I think it's a lot of time with just trees and farms and an occasional covered bridge when there is so much more only a few hours away.