My first epic moment was at a low level when I was running away from a wild mage and his summoned creatures not too far from Riverville, and came to an interesting area with high arches and a carving of a dragon. Then the dragon arose and my final thoughts were "oh, s**t!"
I was also moved when I was doing the Brotherhood of Kor quest, and just about to run out of breath I came up into the underwater temple, and it was just an awesome scene, kind of spooky and majestic at the same time.
I also must say that, during my second playthrough, I used tcl to get a bird's eye view of many places, especially the remote forts and castles, and I was amazed at the amount of detail in the construction of those places where you would normally never see those details just walking or climbing. Some truly awesome vistas, like some National Geographic video shot from a plane or a helicopter!