You may want to get either or both cards. However, if you are looking for redeemable miles or points for the occasional flight, you should consider flying Delta and crediting to Alaska, given the (usually) far greater availability and more favorable rules of the AS program. This would also give you the chance to credit AA flights to the same account if/when AA is the best choice for your routing.

As Southwest absorbs AirTran, the number of destinations served by WN nonstop from ATL may well decrease significantly. But it's hard to argue with the value of WN points for WGA fares.