Here's the Delta program
chart
I also fly coach everywhere since 2001 - either upgrades or winning an unseen lottery (like the last redeye to NYC). The ability to call and talk to a better qualified agent that is willing to move a mountain for you is really worthwhile. The exec plat desk was amazing - was able to get my mile tickets almost at will. They would seriously say, "Okay, if these are the dates, let me spend some time figuring out how to get in business class miles. I will call you back when I figure it out."
It's actually devaluing the program a bit that by using a certain credit card, instead of sustained patronage loyalty, that many of the perks are available. But I guess that will work out for me just in case AA one day discontinues the lifetime card.