I love researching travel and am a fairly experienced flyer. I've spent the thousands of dollars to purchase an upgradeable international ticket - last summer to Beijing (it was worth it) and this summer to London (the flat bed seats were nice). It seems that other airlines (i.e. United) don't charge nearly the amount that Delta charges. However, I've remained loyal to Delta. I've done pretty well with getting upgrades on domestic flights. It's the international flights where I REALLY want the upgrades.