You can spend an afternoon browsing the exhibits at National Center for Atmospheric Research during your travels in Boulder. Attend a sporting event or simply enjoy the top-notch restaurants while you're in the area.
Chautauqua Park is worth a pic or two when discovering Central Boulder. Why not take a stroll along the riverfront and watch the sunset while you're here? It's also full of great shops and restaurants, so you can spend the afternoon having a wander.