Funny thing is, in a sense I'm not an aging runner since I just started a couple years ago. But I hear that - I can feel the need.
The really odd part is that my lower body is almost all slow, lumbering muscle, while my upper body is (seemingly) all quick-twitch muscle. So those lumbering boards are no bueno for me. Also why I realize I have problems when the surf gets bigger than DOH - I just don't have that slow, brute strength to lumber into larger waves. I scratch into sh!t fast, it's just the way I was built. I would bet starting out bodyboarding in my youth has a lot to do with that. Also a major reason why surfing on my backhand feels infinitely more natural than my forehand.
Board-wise, it's funny that I had this figured out 25 years ago. If you're tall and lanky, get a (relatively) tall and lanky board, if you're short and squatty, get a short and squatty board. So laughably simple in hindsight. The way I look at it is, if you're on the wave, you shouldn't even know the board is there because it's that much of an extension of your body and that board should slice through every turn or drop like a knife through warm butter. That's what makes a good if not magic board.
The Hawaii trip was good because that was the first time I was able to directly associate board feel with liters. So now I have an inkling. Somewhere between 30-32 liters is pretty close to what I need.
