We leave for Aruba menana!!! We purchased a TS at the Surf Club on our honeymoon (it was just starting construction), and this will be our first time there, now with 4 kids.
We are basically doing the same - renting at the airport to get to the Marriott, and have it to food-shop the next day. After spending probably 40 hours researching and calling, we ultimately are going with National. They are on the airport, and I can return it at the Holiday Inn nearby and walk back. I tried Economy (which we've used in the past with happy success), but was thoroughly disappointed in the lack of customer service from the person I spoke with (and I was very polite). They were much higher priced (60% higher), and had no interest in trying to compete with the lower price I already had, or to at least offer a discount (time share owner, repeat customer, whatever...).