@MSP_Monopoly - I would start with Frugal Travel Guy's blog. He has some posts in 2008 that lay out much of the technique.
Back to the AMEX companion tickets -
here is a link that compares cards with companion tickets for AMEX - the only card left with a companion ticket is the AMEX Platinum (not Delta). The companion ticket is one of the main reasons that I got the Delta Platinum AMEX.
They should continue to be a benefit of the Gold/Platinum/Reserve card, but not on new offerings. My Mother just used her annual $99 certificate for my sister. It saved over $350 for the 2 tickets. She was planning on upgrading to the Platinum at her anniversary date, but I guess she won't now.