Logan Express in Braintree is (I believe) $7.00 per day to park. You could the grab an Uber to the port (approx 11 miles) …If arriving the day before, right around the corner from Logan Express is a Hyatt -
when we flight out of Boston, this is what we do. Park there because between Braintree and the airport and cruise port is the worst traffic. Call to verify the per day parking rate but that is what we paid last October.