Who'd a thunk it, that we'd be so spoiled for choice? Barry's list look pretty definitive to me. There are two Mahler 7 moments that really stand out in my memory--tiny details really. The first is Abbado's handling of the opening of the scherzo in his CSO recording; incredibly sleazy (has to do with the swift tempo and the accents in the bassoons), and just wonderful. The other is the way Bernstein handles the viola trills (I think violas--I don't have the score in front of me) that introduce the "tango" theme on the oboes in Nachtmusik I in his Sony recording. That timbre has never been exactly duplicated, not even in his remake, and it blew me away when I first heard it--truly a totally new and original sound.
Finally, a slightly sick Mahler 7 story, but one that somehow suits that outrageous, nose-thumbingly grotesque finale. I attended several of the live performances that eventually became Bernstein's second recording. At one of them, I was joined by a very dear college friend (who very sadly passed away from HIV a few years later). In front of us was an elderly woman with one of those poofed up, "steel wool" hairdos that was completely blocking our view. She also spent the ENTIRE SYMPHONY opening and closing her purse, fishing around, and then slowly unwrapping one hard candy after the next. Every few minutes she would repeat the process. It was driving us crazy. I happened to have a box of Jujubees (remember those--little, rock hard gum-drop like candies?). My friend asked for one, and flipped it quietly into her hairdo when no one was looking. She didn't notice. So I did it too. I know, it was obnoxious, but by the time the finale got going her hair had a enough jujubee ornaments to pass for a Christmas tree, and no one was any the wiser. The look exactly matched the tone of the raucously festive ending. We ran for the exists when the performance finished, but I did get to see it a couple of other times without disturbing or being disturbed!
Dave H