I hope its not too late to chime in. You have gotten some great advice. I suggest doing the cape cod rail trail bike path, its very nice, paved and protected from cars. At the end of the bike path, you can use your map to navigate to provinceton, also a nice ride (just choose the bike route that goes along the coast, don't remember now what the roads are called). I think from the start of the bike path (there is a free parking lot) to P-town and back, is around 70 miles. If you want to spend time with family that doesn't want to do that much riding, have them drive to P-town, so you could meet for lunch, and then they could go out on one of the whale watching boats while you ride back.