Both on roiad rides. Carry two CO2s and a tiny little pump for backup. Use "them" (never had to use more than one on a ride) first. Recyle the cartridge when I get home.
When touring, I carry a Road Morph G so I can easily inflate every day.
BTW...For those who don't know, CO2 leaks faster than air. If you use it, delfate the tire completely after your ride and then refill with air. Don't make the mistake of leaving it in and then thinking you have a flat a few days later.