Ive been on a few of these.
Route 66 was cool and I loved the little old towns we found. Nice if you like history but lots of straight road. Not really a great bike road, at least the part I rode on.
Route 1 in Maine is not a bike road. In the summer it cluttered with tourists and has far to many stop lights on it. Its pretty by better by car with AC and tunes.
I think maybe the Kancamagus Highway in the White Mountains should be on the list. That is a fun road. Also Bear notch road (if you dare) is a blast. Don't drive that road faster than your own abilities though. If you do, it will be your last ride.