It rather depends when you arrive and depart and also whether your departure flight is domestic or international. Peak hour traffic can be horrendous and it's not that much fun at the best of times. Whilst a trip into the centre of town can take as little as 40 minutes, it could take you a couple of hours.
If your departure is a domestic flight then you need to shave off an hour to check in, international at least two, so in reality you have five or six hours not counting any luggage pick up from your arrival, unless it is already checked through.
It will be a fairly hurried trip, wherever you go and there's really nothing in the vicinity of the airport itself worth visiting.