Susan, in Aug. 2005 a friend and I did Bicycle Adventure's 6-day San Juan Island tour. It was great. However, there's quite a bit of traffic in the summer and the roads are fairly narrow. They were almost all chip sealed, too. Just be careful. I nearly got hit twice by stupid motorists. The speed limit is 45, but they don't appear to adhere to that.
Now for the good part. Our favorite place to stay was on San Juan at Lakedale Lodge. It was beautiful, charming, and very comfortable. It was between Friday Harbor and Roche Harbor. We ate at a restaurant about a mile from the lodge called Duck Soup that was divine. The cycling on San Juan is challenging for the most part. Don't miss Lime Kiln State Park there. As well there's an English fort that has gorgeous gardens. I don't remember it's name. Also Roche Harbor is fun if touristy on San Juan.
We also cycled on Orcas. We climbed Mt. Constitution. It's 4.7 miles of about 2200 ft of switchbacks. I "cross-trained" on that one and sweated buckets in the fog. Fortunately our SAG van was at the top. In the fog it was just too cold to try to ride back down. Those who did were miserable. I would suggest Rosario Resort on Orcas. We didn't stay there, but the place we stayed has since closed, I think. I wasn't exactly crazy about it anyway. The quaint town of East Sound is on Orcas. I bet there's a great B&B there. We had a wonderful meal there at a restaurant called New Leaf or Green Leaf.
Don't miss cycling on Lopez. It's the flattest and was described as a rolling pancake. We didn't stay on Lopez, but I do recall that there were lovely B&B's there that we passed. We also cycled on Guemes. It's got very, very steep hills. The ferry system between the islands is wonderful.
There's so much to see--gorgeous views, lavender farms, parks, orcas (I never saw one!) Enjoy it. If you're interested, I could dig around and probably find our maps and turn-by-turn directions. You could tailor those to suit y'all.
Susan