Just yesterday I found myself on the phone with DL while working the web site at the same time. I could not tell from the web site if there were upgradable seats. The agent was very nice. It took 1/2 hour of working through flights to find upgradable seats. The web site is great for the flyer who has simple travel plans and does not travel often. The biggest problem I have with the site is I need more time between certain flights then offered on the web site. It would be nice if you could build the ticket by flight number instead of it doing it for you. And, why can't we select our own seats like UA lets you do?