I find knickers to be very useful. Great for temps in the 50's, I layer them under thin tights for really cold morning commutes when I know it'll be warmer for the ride home.
As for shorts within shorts, such as those ZOICs, I don't see why you couldn't wear them for casual road rides. Wear what is comfortable.
That said, I'm eyeing these from STP, but I'm not familiar with the brand. As you can see, different brands will fit different folks, well, differently. Some will love a cut, others will not. It's best to try them on, I think...especially a new brand with which you are not familiar.