Is This Too Late for Foliage?
 

Sat., 10/9 Arrive Manchester, NH
Sun., 10/10 Drive to Middlebury, VT (Middlebury Inn)
Tues., 10/11 Drive to Mt. Washington (Bretton Arms B&B at Mt. Washington Resort)
Wed., 10/12 Drive to Bar Harbour (Claremont Hotel in Southwest Harbor)
Thurs., 10/13 Drive to Portland (Percy Inn)
Fri., 10/14 Drive back to Manchester
Sat., 10/15 Depart Manchester

Are we too late to see good foliage in these areas?

Not really - it may be a little past, especially the Mt. Washington area, but I'm sure you'll see much foliage.
I must comment on your itinerey - this is a LOT of driving for 6 days. The drive from Manchester NH to Middlebury is about 3 hours. You'll see some magnificent scenery however. The drive from Middlebury to Mt Washington is even longer. I can't imagine driving that far, and then driving to Bar Harbor the next day?! Driving times in this part of the country are much longer than they seem on the map. There is so much gorgeous scenery in Northern New England, why exhaust yourself driving from one corner to the next each day? If it's not too late, you may want to regroup and concentrate on VT and NH, or NH and the coast. If you are locked into this plan, be prepared for some major driving - but very scenic
:-)

The lower New Hampshire/Vermont area will be fine for foliage viewing at the time. If you want to see more fall foliage, then head west into the Catskills and Hudson Valley in New York instead of going to Maine.
Zootsi is right. Your itinerary calls for a lot of driving.

Well, unfortunately, we're locked in with non-refundable hotel deposits, etc. We had a travel agent here in Florida plan this itinerary for us and she said she goes to New England every year, so I was confident we'd be okay.

We both enjoy driving quite a bit, so that part doesn't bother me. I just hope we have time to stop at a shop or two along the way.

Will make the best of it and maybe we can return someday and do it differently.

Thanks for your concern.

Nicest town for shopping in Maine on your route would be Camden. Take a drive up Mt Battie to enjoy the incredible view overlooking the harbor. Then have lunch in town. Bring binoculars!
The Vermont Country store has two locations. You'll have to look them up. Weston will be out of your way but the other one should be do-able. I would vote that as the shop in Vermont not to miss. Middlebury is a beautiful town. Take a walk across the pedestrian bridge. There's some lovely shops in Middlebury.
If you like contemporary handmade crafts, in addition to the shop in Middlebury, the League of NH Craftsmen have a shop on Main St in Concord NH.

foliagenetwork.com can help

I was in the White Mountains last weekend and saw more color than I expected in the area around the Mt. Washington Hotel. Just 30 minutes south in Lincoln there was much less color. I posted pictures from my trip on worldisround.com. You can search on my name, jackie macleod. The pictures were taken from the Mount Washington, the Flume and the Basin. You can see the status of the color as of last Sunday (Sept 19).