I think of an upgrade the same way the Supreme Court thinks about pr0n: "I know it when I see it".

At some hotels, that could indeed be the concierge lounge floor or section of the hotel. Kind of depends on whether that in and of itself is an upgraded floor or section. (Imperial Riding School in Vienna is one such example.) But at most hotels, I don't think of having been "upgraded" unless I'm in something resembling a junior suite. In a standard hotel tower, I think of high floor, decent view, away from elevator and ice machine, bed type matching my desires, etc. as basic parts of the status.

Some hotel FDC's will say "you've be upgraded" when in fact they mean "because you are Gold/Plat, we met your basic room requirements." I wish these people could be retrained: I'd rather hear "we're sold out tonight so no upgrades are available, but we still have one of the best possible regular rooms for you" than have somebody sugar-coat it and try to convince me that my non-upgrade is an upgrade.