Cant comment on wearing contact lenses and glasses at the same time, but as far as contact lenses go, I've been wearing gas permeable ones for over 10 years and flying commercially with them for the last 2. Tend to give better peripheral vision during the day and they allow you to put sunglasses on/off as required, but I find EFIS screens and runway lights tend to blur somewhat with them at night, so I always revert to my glasses for night flights.