Another vote for the Cabot Trail. I've done it three times and it's one of the most scenic drives on North America. The Atlantic Provinces in general are also very bike friendly in that pedestrians and bicycles are given a level of respect I haven't seen elsewhere.

Closer to you is the Blueridge Parkway and the Skyline Drive that would be another amazing way to spend a whole summer. About 120 waterfalls scatterred along about 600 miles of parkway. Lots of ups and downs though.