Some of my best moments this year were:
Watching my buddy hook his first steelhead (you should have seen the look on his face - 'oh - sh## what do I do!' 'let him run!' I started to say, but 'pop', I was too late and the line broke. He was hooked though!)
Watching my 'little brother' catch his first wild rainbow on an OP river. Then catch his next. Then his first dollie. All on the same trip.
Watching the same buddy and the same 'little brother' catch their first salmon.

What's really fun, it taking out beginners (wife, kids, friends, whatever) and getting them into fish. The trick is to make them feel like they actually out-fished you. When my wife says - "wow, I even out fished YOU!", I just smile, and say "yep, you did great!" Knowing she'll be more exited about going fishing the next time... (OK, OK, so they really do out-fish me. Sounded like a good excuse anyway...