I have a wedge pack with a spare tube, patch kit, levers and CO2. I carry a schrader adapter and a couple spare cartridges just in case. It sits under my seat and I don't notice it.
I have been completely unable to flat my Bontrager Hard-Case Tires in over 3,000 miles. I run them at 100 PSI. Also, I run 28-32mm tubes inside 25mm tires. You can tell me how bad that is, but the only side effect is when I do have to put them on, I have to be more careful to not get the tube pinched in the rim.
My route has its share of potholes and loads of glass. I actually hit a curb head-on a few days ago. No damage to the rim or wheel at all, and no flat tire. I've ridden about 80 miles since then. This does bring me to my next point. 25mm Bontrager Race-Lite hard case tires don't grip nearly as well when you have to brake hard or corner hard. The reason I hit the curb is because I lost control of the bike (but managed to keep the rubber side down) taking a hard left corner after a high-speed downhill. Another thread, another time.