I went ahead and got the one month basic Expert Flyer subscription and was able to see the availability of upgradeable seats. And it was very helpful. When I called the TK rep, he told me there were no seats available on the flight I had booked, though EF said there was one seat left. I then told him that I had access to the availability data base and he should check again. He looked again and said "You're right!". And now I'm upgraded to a J seat! Thanks, Expert Flyer! Worth every penny!