It is good to know you have only 2 carriers to concentrate on. This is better for earning miles on them faster.

The mileage-earning credit card options can earn you miles too. Check relevant threads in the FT.

Now, you will see a recent post in here about getting 1000 miles on either carrier for a promo that is going on right now. These promos and sign ups for various things or even surveys can earn you a few points here and there. They do add up over time for just some clicking online, etc.

If you are trying to see if you can get a free ticket round trip (RT) from the west to the east on one of those carriers, that is 25,000 miles for the free ticket. Though you could gain that many miles and do this option, there may be better ones for your value.

Instead, consider that it may be more worth it to BUY that RT ticket now because the rates are so cheap these days. Then you will earn miles (and more status on the airline by doing actual flights) which you can use for better trips later on. It's all about maximizing the use of your miles, I think.

An example of this might be to save up miles to use for trips to Hawaii which only require 10,000 more points on AA and I think only 5k more on DL. These flight, however, can costs several hundred dollars more if you pay out w/cash. SO you can already see how miles will be better to have avail.

A few Web sites come to mind for BUYING cheap tickets if that's your game. www.smarterliving.com comes to mind. There are many others. Check the threads in these forums and posts to see more. People in here have covered everything indeed!

You have to do a bit more searching in here, or if you like, email me, for example, for a few more tips on all this stuff. The address is in my profile here.