Enjoying the San Juan Islands on a bike is so easy it's almost like going to a bike touring theme park or something. We enjoyed it so much we spent most of two weeks on the San Juans and the Gulf Islands (the Canadian edition).

Basically, you can just roll your bike onto one of the many ferries going to many different islands. You don't have to box them up or in any way justify the fact that you're a cyclist. You just pay a small fare ($15 or so in the San Juans takes you round trip to all the islands) and roll onto the ferry. And you usually get to get off before all the cars.

Then, when you arrive on the island of your choice, you do a moderate ride to a campsite that works, where you'll often find hiker-biker campsites, which require no reservation. So you set up camp, watch the sun set, and maybe the next day go for a ride without your load, and then maybe move on to the next island... or maybe stay for another sunset.