When do you get a shiver up your spine, goosebumps, the feeling of "oh-man-that-is-just-too-cool!"? Not just in the OT, but in the PT as well.
*When the clones are marching to the Imperial March.
*When R2-D2 is safe after the battle of Yavin.
*When Han saves the day by shooting the TIEs in the trench.
There are more, I know, but those are the ones I can think of off the top of my head. What about you?