Farming isn't fun at all.
I don't see myself going through inferno myself. I figure my barbarian will hit 60. My monk will probably slowly crawl to 30+ since she's an alt that I only play as when two of my friends are on. They also play as alts so one of us is never way ahead/behind.
I doubt I'll start a third character. Most likely, I hit 60 with my main and maybe my alt, play when friends are on and still into the game, then take a break until the expansion pack comes out.