For several different kinds of enemas I enjoy, here are my enema 'wow' points in the order they occurred to me. I love enemas. Let me count the ways:
Feeling water at the hottest comfortable temperature slowly flowing into me during a long, slow, 30-minute enema of the relaxing variety.
The same while 'ghost fucking' myself no hands to orgasm or near orgasm with my Model B nozzle--not quite as relaxing, but a fun 'workout' for the sphincters and pelvic floor muscles
Any other kind of enema-induced or enema-enhanced orgasm
Feeling the internal chill of cold water slowly flowing into me
Feeling and watching the ridiculous distensions resulting from 3 or 4 quart fills
Rapid-fill-rate enemas, using I-inch-inside-diameter tubing and nozzle, that allows filling at 10 or 20 times the normal fill rate, (at a safe, low pressure of course)
Slow, relaxing, 5 to 10 minute expulsions, especially with the hottest comfortable water or solution
Using body positioning and abdominal massage to enhance expulsion: the internal sounds of sloshing, swishing, and gurgling; the sudden release of a quart or two of trapped water; the flat or sunken abdomen resulting from near total expulsion
Fast, explosive expulsions (in the tub with curtain draw by necessity), either induced by a hot, high-fill-rate enema, or 'pulling the plug' after a long retention
Expulsions with multiple intense waves of peristalsis--defined as the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward--which for me often produce highly pleasurable, full-body convulsions, involuntary grunting, and the near total expulsion of 3 or 4 quarts in less than 30 seconds.
After cleaning out, repeatedly going between a big distension by 3 or 4 quarts to an almost completely empty colon and a flat or sunken abdomen
At the end of a session, that wonderful feeling of contentment, well-being, relaxation, lightness, and energy
At the end of a session, (1) feeling like I can almost press my bellybutton into my spine, (2) seeing a side view of myself in a mirror that shows my abdomen has half the width of my rib cage and my butt, (3) being able to easily and comfortably fit into my tightest jeans, (4) feeling sexually aroused, especially in the anal-erotic way that craves (another) orgasm while anally stuffed with a large butt plug or something better