All my bikes have the Brooks B17 S. Out of necessity I wear the Lycra shorts but can't wait I go back to De Anza this winter and ride naked. For good health, I'm out of the shorts as soon as I finish riding. The worst is to stay and sweat in your shorts! I've ridden 7200 km this year so far and starting a 1200 km ride on Tuesday from Hamilton, On to Albany, NY via Niagara Falls, NY Bike route 5 to Syracruse, North to Kingston, On, 1000 Island Bikeway to Montreal and then south along the Hudson Valley to Albany.
Rarely ride nude, and when I do it is only a short distance.
Used to ride in short running shorts all the time.
Chafing on my crotch and thighs was very uncomfortable, so I now wear standard bike shorts.
Do bike shirtless whenever it is warm enough.