Would you say your route is better than ACA's and if so why, i.e. less traffic, more scenic, more services, etc.?
Well, maybe it's a bit cheeky of me to say my route is better than ACA's Atlantic Coast Route through Maine, but yes, I'll go ahead and say it!
Here's an elaboration:
-- From the NH/ME border up through Wells, I wouldn't change a thing. The coastal road there is beautiful, right on the ocean. It'll be busy in July and August, but beach road busy, not highway and truck busy. Doable for most cyclists. And outside of those months it's much quieter.
-- North of Wells, if you're not in a hurry you can take Route 9 to stay along the coast and go through Kennebunkport, which is a cutesy tourist town. It will wind around to Biddeford-Saco, where you can jump on the Eastern Trail (also the East Coast Greenway). The trail will take you almost the whole way into Portland on pretty hard packed surfaces. You'll go right across the beautiful Scarborough Marsh. One or two road spots in South Portland, but not bad.
-- I would definitely not go inland at Kennebunk, the way the ACA route goes. There are really no interesting towns on that entire arc around Portland, until you hit Freeport. Some of the roads are nice, but not nice enough so as to avoid Portland. I live in Portland and bike here daily. It's a city of 65,000 people, and almost all of the roads are quite manageable. Especially if you come across from South Portland, hit the main commercial area, and then continue out of town on the East Coast Greenway route, there's nothing a fairly experience cyclist would have trouble with.
-- North of Portland along the coast to Freeport is good cycling as well. These are not sleepy back roads, but the traffic is pretty moderate.
-- From Freeport to Damariscotta, I think the ACA Route gets it right, for the most part. There are some nice sections here, and then some unavoidable stretches of Route 1. Route 1 here isn't terrible - there's usually a decent shoulder. But it's a steady stream of traffic pretty much any time of year.
-- From Damariscotta to Belfast, I would do it differently from the ACA, following some version of the route I linked to in an earlier post. Waldoboro and Camden are nice coastal towns, but in my opinion not worth all the extra time on Route 1 (and Route 90, which is a cutoff of Route 1 that most through vehicle travelers take). Route 52 from Camden to Belfast is very nice, so that's a plus for the ACA Route. But I'd bail off Route 1 much earlier, as per my linked route. My route through this area is a bit hillier and a bit more convoluted, but there are some great stretches of road here, and for the most part very quiet. The towns are small but pretty neat. Union, Appleton, and Searsmont are all traditional small New England villages.
-- Past Belfast, there's an unavoidable stretch on Route 1. It's not as bad as Route 1 further south, but it's still pretty busy most of the year. Some of the towns here are interesting, though. And the Downeast Narrows Bridge Observatory is a must see on a clear day, as is Fort Knox right next to it. I've never ridden the 176/172 roundabout way to Ellsworth, but I suspect it's pretty quiet and worth the detour off Route 1.
-- From Ellsworth south to Bar Harbor, I think it's a true shame that both the ACA and Northern Tier stay on Route 3. That's a huge sprawled out commercial area. If you like mini golf and other tourist traps, you'll find it here. But there's a much nicer backdoor way down to Bar Harbor. You take Route 230 out of Ellsworth and follow it almost all the way, until you hit Goose Cove Road cutoff back to a later section of 230. Then you're right near the bridge to Mount Desert Island and Bar Harbor, where you have to rejoin Route 3.
There's a lot to take in here, and this is all probably better placed in a new thread. Not sure how to do that, exactly.
Happy Riding! I have to get some work done today!