One of the rides I want to do this summer is a day ride on the North Cascades Highway (from the Seattle side). I'm thinking I'll start out of Marblemount, and just bike east for as long as I'm having fun (Rainy Pass? Washington Pass?).

I'm wondering if anyone has suggestions of where to park that is convenient but won't antagonize the locals. Suggestions of a start location other than Marblemount are welcome too. This would be on a weekday.