I can't say enough good things about renting a car through National. They make it so easy. Join the Emerald Club and when you leave MCO you just walk to the row of cars and take one. You drop it off close to the Port and a free shuttle has you over at the terminal in minutes. Coming back, the same shuttle picks you up and you its easy to drop off you car at MCO too. I think it was about $90 each way, including gas, and tolls, when adding it all up. I like that you are in control too and can make stops for supplies or to eat at a restaurant, etc.