I second the suggestion to do the 3* Priceline thing in the MCO area....prices are higher than they used to be (may take a bid of closer to $50 now), but still quite a bargain...and perfect for your needs.
They book at the Hyatt inside the airport, the Marriott, Holiday Inn Select, Sheraton Suites and sometimes the Crowne Plaza....all are quite nice. All offer complimentary shuttle service to the airport 24/7....so if you wanted to return the rental car Sunday evening you could ****tle back to the hotel and not have to mess with it before your early flight.
You can get a room through Priceline at one of those very nice 3* properties for quite a bit cheaper than you could book a room at directly at someplace like LaQuinta or Fairfiels Inn.