Since you live in HOU, you might take a look at the Southwest Visa.

1 RR credit per $1200 spend, so a RT on Southwest for $19,200. And double that rate with their partners, so potentially a RT for as little as $9600 spend. That's a pretty hefty rate of return.

If you have a shot at accumulating 100 Southwest RR credits in a year, and have someone to travel with, the Southwest Companion Pass is a heck of a deal on top of the free trips. I'll get $3000 this year in tax-free value ($30 extra per RR credit) flying my son around with me, without too much effort.

The Diners Club card yields points that are highly coveted by many (check Coupon Connection), and, as I understand, it you can transfer them to anyone. I'm pretty new at the DC card, but I've been told that sometimes they have specials where you get bonuses for transfer (so at a better rate than the Southwest Visa for transfer there), and I am therefore piling up some DC points. Diners also has what I am told is about the best CDW protection when you rent cars.