If you're going to stay at Disney and spend a majority of your time visiting its parks and attractions, your best bet may be to use the thorough and free transportation network that runs throughout Mickey's realm.
Guests at Disney resorts and "official" hotels get unlimited transportation via bus, monorail, ferry, and water taxi to all of Disney's major parks from 2 hours prior to opening until 2 hours after closing. There also is service to the hotels, Downtown Disney, Typhoon Lagoon, Blizzard Beach, Pleasure Island, and other resort areas. Disney properties offer transportation to other area attractions as well, but you'll have to pay extra.
The system has several advantages. It's free, possibly saving you on car rental, insurance, and gas. You also don't have to pay for parking ($7 per day at the theme parks). You may avoid a wait to enter the parking lots, and, if your party wants to split up, you can board a transport to different areas.
The disadvantages? You're at the mercy of Disney's schedule. Sometimes you have to take a ferry to catch a bus to get on the monorail to reach your hotel. The system makes a complete circuit, but it's not necessarily the most direct path for you. It can take an hour or more to get somewhere that's right across the lagoon from you. This is especially true if you stay at the Disney resorts that lie in the outer reaches, such as Fort Wilderness. If you decide to forego a rental in favor of the transportation system, you'll also be limited to the areas the system serves, which means you're stuck in pricey Mickeyville.
If you have time before locking in your trip, call tel. 407/824-4321 and ask the information specialist for a Disney World Transportation Guide Map. (It shows where various resorts are in relation to the attractions you want to visit.) Disney may refuse to mail one to you, but you can use the maps in this guide, pick up a guide map when you land, or view a more generic map and download it at www.disneyworld.com (you'll need Adobe Acrobat Reader). When you get on the website, click "Reservations & Info," then "Transportation," then "View and Download Some Maps."
The best rule when using Disney transportation: Ask the driver or someone at your hotel's front desk to help you take the most direct route. Keep asking questions along the way. Unlike missing a highway exit, missing a bus stop means you may reach your pension before your destination.