My main concern with going mid-summer is that, especially in the sections in the southern tier (south of Portland) you'd need to be on and off Rte 1 to hit the scenic shore roads. The heavy summer tourist traffic would make the touring much less enjoyable. Yeah, you can get around in it, but since there is no lane splitting in Maine, you'll be caught in some stop and go traffic for sure.
As a bit of a Down East gastronomic teaser:
I've been working up in Bangor for the past 2 weeks (anyone miss me?). On the first day, one of the local guys took us over to a tiny restaurant on the Brewer side of the river for lunch. A tiny hole in the wall sort of shack, but it literally hangs off a cliff over the Penobscot. The point of this lunchtime excursion was that the Eagle's Nest Restaurant serves up possibly the best lobster roll on the planet!!
The plate comes out with a heaping mound of lobster meat piled on it. Savvy locals order theirs with two buns as there is plenty of meat to fill both and still have some left over. There was at least 10 full claws of meat plus some other knuckle pieces in the pile. The meat was sweet and tender and the dressing was not overly mayo'ed up. They serve it on a bed of home made fries and include a side of home made cole slaw. Fantastic! We ate lunch there 3 times a week.
Definitely worth a stop when you are in the area. But Bangor is pretty far from the picturesque coast (~45 mins. west of Bah Hahbah) so the Eagle's Nest wouldn't fit very well into a coast-line ride.