Our lodging was at the SouthCape Resort located in Mashpee which is an hour from downtown Boston or an hour from Provincetown. The Mashpee traffic circle is a challenge (and fun). The drive to Martha's Vineyard ferry is very scenic throught the historcial area of Falmouth. Leave lots of time to drive to Provincetown as it is a one-lane highway and very busy. The beaches there are fantastic for sand dunes and swimming.
Quick Tips:
Martha's Vineyard is the best--the way to see it is to leave your car on the mainland, take the ferry (only way to get there) and take the 4-hour bus tour of the island. It stops in Edgartown and and Gay's Head, finally bringing you back to the ferry for shopping.
Don't miss going to Sandwish to the World's Largest Blown Glass Museum and have lunch at the Daniel Websters Inn. For kids there is the Briar Patch Museum and Brair Rabbit.
Best Way To Get Around:
Walking: beaches and shopping.
Driving: DON'T drive in downtown Boston unless you are suidecidal. Take the Metro.
Buses: Martha's Vineyard tour and Red Trolly tour in Boston.