Hi Charles,
KBED (my home base) is ~13 miles from Cambridge, and has rental cars (Hertz & Avis), spotty public transportation and a Cirrus Service Center (East Coast Aviation 781-274-0105) in case you wanted to schedule some service while you plane is static for a few days. There is a $10 landing fee, and $12 ramp fee per night with either Signature or Jet Aviation. Handling fees are waived with a fuel purchase.
KOWD and KBVY are each ~25 miles, I am not sure if they have rental cars. Similar overnight fees, and no landing fee.
Please give me a call if there is anything I can help you with while you are in the 'hood 978-835-4004.