I carry two CO2 cartridges along with a spare tube. I know that if I use the CO2 that I will need to deflate and reinflate the tube when I get home but that is not a big deal.

I used to have a long pump mounted below the top tube of my road bikes but with mountain bike frames that is not practical. I prefer to use the same repair kit under my seat for all my bikes and so have gone the CO2 route.