Though I managed to escape at the age of 14, I am a native Cape Codder (who used to fly extensively on Air New England and PBA) and, therefore, feel compelled to chime in on this topic. I agree with others that the bus/car/boat combination is a waste of time in the absence of substatial savings. I suggest you refer to expedia (instead of travelocity) to research air fares -- they offer fares on UA, CO, and US for around $240 from DCA. If you're willing to leave from BWI, you could probably do a bit better by getting separate tickets for BWI-PVD and PVD-MVY.