I Found Martha's Vineyard

I've heard tales of Martha's Vineyard, read books where the characters visit it or live there, seen it in movies and TV shows, but up until today, I never knew where exactly it was. I could have, at any point, gone to Google and checked, but I didn't. There wasn't a need until today when I was researching a scene. I wanted the main character to go there for a party, one that turns ugly and gets her into something far more dangerous than she can handle. The problem: it's too far away from New York city. I don't want to put my electricity-frying character in a car for that long, and I definitely don't want her on a boat. Both scenarios would cause too many problems at the wrong point in the story. She doesn't want to be in either of those situations, either.

Now I'm tasked with finding a very nice house of the rich and famous somewhere closer to New York. And it needs to be a house because it needs to have a basement. Unfortunately, none of my three maps have little labels that say "sprawling properties here." Back to the Internet I go.