All great roads, but some of the best are just named country roads that have no real route number. Best thing to do is to just plan a drive, post it up and see who signs up/shows up. Too big a group can be problematic also because you draw unwanted attention. When I did this with the Audi crew years ago, we had to break up into smaller packs in certain segments to avoid unwanted attention.
BTW...OP, where in MA are you?
Audi S6 * Audi S3 * Porsche Cayman GTS
--Former BMW M3 owner