Budget has a great loyalty program. Check out their website. The high points:

Besides the merchandise (which I don't want), you get 1 point for every dollar you spend, including taxes, fees, gas, insurance, etc. If you book online, you get double points, and if you redeem an award online, you get a 20% point rebate.

With double points and the 20% rebate, you get a free day for spending about $240 (a typical weekly rental), and a free week for spending about $600. Not too shabby.

On top of that, you can also save up for vacation packages, which include 2 or 3 nights at 5 tiers of hotels. They range from $1,200 to $8,000 spent (the high end being Ritz-Carltons).