I just responded to a post about riding in Maine, and I thought I'd plug Owl's Head Transportation Museum. The museum has an amazing collection of cars, trucks, engines, bikes, and more. The riding around the museum - Rockland, Owl's Head, Spruce Head, etc - is sensational, and not usually too crowded.
I'd really, really recommend their Vintage Motorcycle Meet & Antique Aeroplane Show, on Sept 4-5 this year. It's a truly amazing exhibition of classic bikes, out on the tarmac along with some gorgeous airplanes. Every imaginable Norton, BMW, Ducati, HD and more, most in prime condition, are grouped by country. And the bikes parked out front are an eyeful, too.
(wife - mine; Beemer - someone else's)