This is a decision I also made. Living in the Pacific NorthWest, I am fortunate to fly AS a lot. However, for my flights back east and elsewhere, my criteria is to choose an airline partner of AS. This is the simple reason I don't fly UA (unless absolutely forced by price)--they don't partner with AS. I then throw all my NW, TWA, etc. miles to AS. My AS miles account is then available as you've pointed out for partners that go anywhere I want to go.