Please, do everybody a favor and don't use CO2.
Having said that... I had great luck with Schwalbe Marathon tires. There are many models. Generally,the level of protection goes up with price, of course. I'm currently commuting on mid-range Marathon Plus HS348 and I don't get flats from glass at all. Once it was punctured by a staple and once by some sort of hair-thin, tiny wire.
I carry two spare tubes. If I get a flat, I change the tubes and patch the punctured tube later at home. I don't patch on the road. I like to do this at home, with clean hands to make sure it's patched properly.
I don't need so many tubes as to buy them in bulk. I get maybe one flat per year.
I try to swap the tires every few months, if I remember. I usually replace the tires every Spring, but I ride every day pretty much. Every Spring I do an overhaul: new chain, new cables, new tires.
You can also add tire liners. Green Slime seems to be most popular. Although, I had mixed luck with those. They sometimes shift inside the tire and can cause pinch-flats.