Below numbers are percentages of net (after tax) income.
21% of my income and my wifes income combined goes toward the (mortgage + property tax + home owners insurance)
8% goes toward utilities (gas, electric, cable/internet, cell phone, water, trash)
10% goes toward loans (car, student)
I usually budget about 15% a month for general spending (groceries, entertainment)
That leaves us about 40% to save/invest.
edit: As for the mortgage, my wife and I decided to buy a house that either one of us could afford on our salary alone. Much more financial freedom and less financial stress. If one of us loses our job, or decides to quit, we don't have to worry about how we will pay the bills.