Good question. There’s a free shuttle bus for students that runs down the mall – as RogerJuice mentioned – as well as Target/WalMart/grocery stores/restaurants. There is a small village just north of campus that has a few shops and restaurants, and both Stony Brook village and Port Jefferson village are a few minutes away, and those are accessible by county bus (which is $1 for students) as well. So yes, it’s spread out a bit, but everything’s reasonably easy to get to.
Chris