I use the Alaska Airline B of A signature visa. It's $75 a year and you get an annual bonus of 2k miles. There is no real credit limit, no mileage limit, and the miles are good on Alaska, Continental, American, Hawaiian, British, Northwest, and a few others. You get 1 mile per $1 spent unless it's on alaskaair.com then you get 2 miles per $1 for tickets. Also you get a $50 companion fare every year. Basically buy one full-price ticket anywhere and get a second on the same flight for $50 + tax and fees (ends up being about $60-75 total for the second ticket).
This card works great for me as Alaska is headquarted in Seattle so I can go anywhere using them, especially now that they have flights to New York, Miami, Boston, DC, and a few other east coast destinations. If Alaska does not go there I use American or Northwest and still collect Alaska miles. Redemption is 20,000 miles for free domestict round trip on alaska or 25,000 for free domestic on any of the other domestic airlines.
If you are in the northwest I reccomend this card, otherwise there are alot of others to check out. Another great card is the REI card, and that does not even have a yearly fee
-spike