I agree with peachfront, and the other have provided good advice as well. Thus, I will add my story for a data point.

We are a Disney family, and my goal is to reduce the cost of travel to/from both Orlando and Anaheim. While we could drive to California from Oregon, we need to fly to Florida, as a car trip would be too much.

To accomplish this goal annually, I started looking into companion airfares as a way to reduce the family's costs. There are options from Alaska, Delta, and US Airways available that work well. After research, I went with the Delta Platinum AMEX for several reasons. First, it provided the lowest companion airfare costs when accounting for the annual fee, too. Second, it provides a good set of ancillary benefits for the trip itself (boarding, baggage, reduced SkyClub access, etc). Third, I watched the various sign-up offers and when the offer reached $40k RDMs and 15k MQMs, that seemed pretty good.

That was it, until I started looking around. Since I travel once a month for work for a few days, I decided to review hotel rewards programs. Since Hilton had a variety near my work locations, good elite benefits, and several point usage options, I decided to concentrate on Hilton. Well, this led me to review the various Hilton co-branded cards, and I currently settled on the AMEX no annual fee, since I will be able to earn Gold status via hotel hopping.

Currently, I'm looking into other cards that provide recurring benefits that would pay for the annual fee, such as other hotel or airline cards.

As Gary says on the View from the Wing blog, there are three types of cards: 1) those used daily, 2) those we have for the benefits, 3) those we get for the sign-up bonus and then toss. I choose to concentrate on #2, while I decide what should be #1. However right now, Hilton in my #1 as I get ramped up.

Good luck, and I hope this helps!