This is a fairly easy walk to get to the swinging bridge and there is another fairly easy walk that leads you to beautiful waterfalls. This is located in between Libby and Troy so it isn't a very far drive from the festivities.
Go take a drive on the infamous Going-to-the-Sun Road, soak your feet in Lake McDonald (which is the largest lake in the park with rainbow colored rocks), or go for a few day hikes and you are sure to see some wildlife! I recommend getting there as early as you can because it gets VERY crowded in the summer time.