If you're flying Delta at any point in that period (how could you, with your busy car-renting schedule?), be aware that Delta is awarding 2500 Skymiles for booking an Avis or Budget car rental through Delta in conjunction with the flight booking. I wonder if that stacks with the 3,000 Skymiles Budget is offering. They're also offering 1000 Skymiles for booking reservations with other car companies.