I recently traveled with my family from Bridgehampton to Sag Harbor and used https://ewlimo.com/bridgehampton-to-sag-harbor-luxury-car-service/. I booked a large SUV, which easily accommodated me, two children, and our luggage. The car was clean, the seats were comfortable, and the children were easily accommodated. The driver arrived on time and immediately helped load our bags. I liked that I could choose a car and see the price in advance, without any surprises. We chatted freely and enjoyed the views along the way, and no one worried about parking. I think it's worth paying attention to the capacity and driver reviews when booking.