I usually don't recall an experience of going through a roller coaster inversion, probably because the perception of traveling upside down looks too unfamiliar to remember apart from the everyday right-side up point of view, HOWEVER - I do remember that Volcano, The Blast Coaster's heartline rolls were rather amazing, ESPECIALLY the first one that high up in the air, providing a pretty incredible experience of having an aerial view "roll over" as you "roll" through the heartline.
So that's actually one of my favorite roller coaster moments as well.