Tino- Your Marriott trick is truly creative. I especially like the gift cert idea because if I know I'm spending 2 weeks on the road in Marriotts, that's straight cash in the bank! Your described scenario is pretty awesome.
As for the Southwest trick, I have a friend who flies LUV on a connecting flight every week, and he always does it as four one-ways. It costs him $15-20 more than 1 roundtrip, but he gets twice as much reward.
JBird - As far as the *cars* go, I think Budget is the among the best in terms of selection. If I really want an SUV or a convertible, I can always get one at Budget for far less than Hertz charges. And the Jag is a nice touch, too.
The main area that Budget needs to improve is service and consistency. Hertz blows every other car company away in the customer service area - I think everyone pretty much admits it, too. But I don't complain too much as long as the goodies keep rolling in.
Basically, I'm a whore for free merchandise - especially golf stuff. That's why I dig this program so much.