As far as classes go, I'm 58 years old and have been boating my whole life. My grandfather was a fish boat captain with the Menhaden fleet out of Reedville, Va. My father served aboard a CG cutter in the South Pacific during WW II.
I've taken 5 courses in the past 16 years, one with the CG Aux and 4 with the Power Squadron, of which I am a member. All classes were enjoyable, worthwhile and I learned a few things to boot.
Yes, I learned many years ago that if you don't respect the water, it could cost you big time.