Thanks everyone for the tips . . . pretty humid the days I was there. If anyone stumbles across this thread, here are a couple of the routes I took (roughly - I missed a couple turns and have moved the start/end a bit to protect the privacy of the rental we were in). Feel free to copy for yourself if you go. Overall was really nice biking - SI has a few short hills to force the legs to work just a bit, but nothing to ruin a vacation.
https://ridewithgps.com/routes/28277395
https://ridewithgps.com/routes/28268023