There were lots of "standard candle" kinds of things that could be reported, such as being able to spot the brighter members of Stephan's Quintet in an AP six inch. But that's not what left the strongest impression on me.
It was blackness.
The first clue this would be the case was the Pipe Nebula. Every time I would look in that direction, it would distract me... and for a while I couldn't figure out why. Then I got it: it was like seeing my blind spot take shape in the sky. It was triggering some kind of reflex, being so black against the semmingly bright milky way (it was possible to hold your hand near the ground and see a distinct shadow).
The same theme carried forward into M8, where we were able to see Bok globules in the 12.5, or M16, which usually is a boring smear in my scope. There, it showed a wealth of filaments, blobs and all manner of gradations of light and tone. The sky took on the nom de plume "Aperture Helper" as the joke du jour, but it was very true. Particularly striking was B86, like a dark lake rimmed by faint fire.
The Pelican and North American nebulae were cleanly defined, and the Veil was an easy target in binoculars... but for the first time ever I was able to make out filamentary structure in the middle portions. The brighter portions were breathtaking to the visitors.
M81 looked like a miniature M31, bright and dusty, and was a real crowd pleaser, so easily seen in detail.
But in some ways the most spectacular object was, of all things, M11... which I only looked at grudgingly because it was so bright. But oberver after observer kept making noises about it, and finally I took a look.
Wham. Down for the count.
That's where the other silly joke of the trip came into play: the 3D Option Got Turned On Big Time. Between the exceptionally black background and the very fine seeing, the broad difference of magnitudes in the stars lent the illusion that the bright ones were in front of the dimmer, with an eternal darkness behind. It literally looked as if it extended from the eyepiece to infinity.
Still, I spent more time simply scanning the bright areas and digging up the wealth of dark nebulae, seen so starkly in such a perfect sky. It made me understand so much more thoroughly the fascination Barnard must have had with these holes in the sky; seen in their own realm, they become an almost zen truth where darkness defines the light more perfectly than the light can itself.