RatherBeOnATrain

I collect Thrifty's Free Day certificates instead of miles. Anyone have any thoughts on the best way to use them, e.g. get the most bang for the buck?

My thinking is to use them:

(1) At non-airport locations since airport locations will still charge you the airport access fees and tourist taxes.

(2) For mid-week rentals, when the daily rate is highest.

(3) For four 4 day rentals in order to avoid getting charged a weekly rate (though I'm not sure if using a single certificate on a 4-day rental turns it from a weekly rental rate to a 3-day rental. Anyone know for sure?)

(4) For 1-day mini-van rentals at home, in order to use the van to haul 4x8 sheets of plywood, bags of landscaping material, and other heavy stuff home from Home Depot/Lowes/other home improvement stores.

Any other pointers?