In spite of getting three credits instead of four per round trip now, I still prefer Southwest's program -- it's convenient for the destinations I want to fly to, and I've just been able to rack up awards with such ease and use them when I wanted. Any vacation travel I do, I do on a free WN ticket. It's a beautiful thing.
I've calculated it out a couple times, and if I had been using CO or AA (my two other best options), I would have maybe one or two free tickets in the last four years -- instead of seven from Southwest.