The loans based on cost of attendance are designed to cover your necessary expenses, and in my experience far exceeds what is actually needed. My school estimates $23k/year total for "living expenses" (housing, utilities, personal expenses, and transportation). I live with roommates, picked a cheaper but still nice apartment, shop sales, and budget wisely and spend an average of $850/month on rent + utilities + groceries + gas + fun stuff (going out to eat, bars, movies, travel, etc. - which I do plenty of for my preferences, though perhaps less than some of my classmates). And then obviously there's my cell phone bill and health insurance/healthcare costs as well, but I am still on my parents' plan for those and have something worked out with them, so those are separate from my monthly budget.
I would not recommend taking out the max amount for cost of living if you can avoid it because it'll bite you in the @$$ later when you start paying it off. Every dollar less you take out in loans is an extra dollar and change (don't forget interest) you can spend on a house, car, trip, etc. sooner after you graduate. Not saying make yourself miserable to save money, but you can absolutely make smart financial choices and still have a good time. Once you know how much rent you'll be paying, you can meet with your financial aid people to come up with a reasonable budget for your needs.