If you're a golfer, you should check out the golf course or the driving range that the wedding is at!
Chautauqua is at the base of the flatirons (an iconic boulder photo spot), there are several hikes that start from here if you're feeling active, or you could just go for the view/photos!
This is old town Boulder, it's a great place to get food, wander through shops or see local street performers!