After a good push from ameerat, I checked out the 'Sunny 16 rule.
Basically it's just saying that on a good day with good light, you can start your calculations from f16 - shutter speed (1/ISO) - ISO. That's your given in any exposure equation for that light condition? (I'm ignoring the super bright 22, the cloudy 11, the near total darkness 1.4)
It's not telling me that f16 is the ultimate great light aperture, is it?
So if you go up an f stop (from f16 to f11) then you need to increase the ISO a stop (100 up to 200), OR increase your shutter a stop (1/125 to 1/250) ... right?