Whether it's by botting or just old fashioned questing and grinding, of course. Also, there are a few good reasons to have every class capped at max level.
1. So you'll always have a different class to play if you're bored.
2. Assistance from professions. (Crafting BOEs, gathering herbs, ect.)
3. Using them as cash cows if necessary for gems and enchants.
Thoughts?