Hi Yvonne,
It sounds like you have a fantastic vacation with your three princesses planned! We love to spend a day or two at the beach to relax after an action-packed Disney trip. Disney actually has a beautiful resort at
Vero Beach that is a lovely retreat from the parks.
The car rental companies Alamo and National both have rental offices located on Disney property, at the Car Care Center (which is located near the Magic Kingdom and is easily accessible via a free shuttle from your hotel) and at the Dolphin hotel (which is near Epcot and the Hollywood Studios and is easily accessible with regular Disney transportation). To arrange for your car, you should contact the rental companies directly.
The National rental website is
www.nationalcar.com. The Alamo rental website is
www.alamo.com.
If you would like to arrange for a shuttle to pick you up to bring you to the Car Care Center, the concierge at your resort can help you. Just stop by the day before you intend to pick up your car. When it is time to return the rental car, you will be able to take a shuttle back to your resort from the Car Care Center. I've done this many times and it is very convenient and reliable.
Have a great trip!
Tanya