I think your experience (certainly the part in the air) is representative of Delta. The in-flight service is generally excellent; the front line staff are often excellent - it's the management and their policies that cause trouble and resentment!
As for using upgrades, I just booked flights from London-NY for late April, out via CVG, back via ATL. There appeared to be a lot of avialable upgrade inventory. I got BE seats on exactly the dates and flights I asked for (which virtually never happens). The agent also offered me the seats on several other flights on the same days where there was upgrade capacity.
[This message has been edited by james (edited 02-28-2001).]