<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by nsx:
But you still get double credit for on-line bookings, and you still earn a free, unrestricted round trip for 16 credits. You can't beat that.</font>
No one has mentioned the huge benefit in the Southwest program that kicks in after earning/tranferring 100 flight credits: all of your awards are doubled in value with the Companion Pass.
That, along with the promo at Diners Club, would allow you to get a free, unrestricted round-trip ticket for every $6,000 you spend ($12,000 = 24,000 DC points = 1 RR ticket = 2 free tix with Comp Pass)
Some programs are getting better - you just have to know where to look.