I have The Sims 2 + Nightlife, Open for Business, and University (hooray for finding expansion packs at the thrift store! 😛 ). I always am obsessed with it for a short time, then I try to do a project that's way over my head, and I give up on the project for awhile.
My most recent big project was creating an entire coven of adult and teenaged vampires, and two humans (to make money, you know). I finished, but I can't keep track of eight sims at once. They've already set the stove on fire three times in ten minutes. =.=