I went for four years. A few in my class did it in three. I'm glad I went four years, since I could kind of slack off my school work after I was accepted and had my most fun my last year. From a financial perspective, it makes most sense to go three years, obviously from one less year of undergrad expenses, but also because of the opportunity cost. You'll graduate a year later than you could, causing you to lose a whole year's salary if you do go a fourth year. But at this point in my life, I'm glad I did live it up while I still could.