MMORPGs that won't destroy your life

If you don't understand the incredibly addictive qualities of MMORPGs, Slate provides a good explanation today, along with comparisons of two of the better games going: World of Warcraft and City of Heroes.
Wanna know how close I am to trying City of Heroes? Uh, where's the nearest Best Buy? Actually, I really can't justify a monthly subscription (to my significant other, that is), but they do sell those convenient prepaid 60-day game cards, hmmm.... "I don't want a lot. Just enough to wet my beak. Understand, paisan?"