I've played about four days a week for the past sixteen years. (I'm 33). You'll soon discover that the basketball played at your college was pretty shitty basketball (at least it was at FSU. Much better at my law school). You'll also peak in about three or four years.
There are lots of pickup games all over the place - and I live in a fairly small city - Tallahassee, FL. In the spring, for example, I play in two different church leagues, a weekly lobbyist/legislator game, and then one regular outdoor court. When the leagues/session end, many schools/churches have an open gym night. And there's always the local universities, which for a relatively small monthly fee, always have open gym.
One thing I love about basketball is it is as cardio-intensive as you want. Play hard and you'll burn a lot of calories. If you're tired, slouch a bit and cherry-pick. But most pick-up players are lazy and you can score a ton just by hustling. I frequently drink two gallons of water in the summer on an outdoor court. It's also great for networking.