My parents come to visit in August. We spent a day hiking and boating in Glacier National Park, then spent a couple of days in Whistfish Montana and even got to do a zipline! Then we traveled up to Canada to visit Waterton Canadian National Park before heading to Missoula for shopping.
I enjoyed the entire trip, but my favorite part had to be Waterton. Everyone in Montana has visited Glacier, but I highly recommend making the extra treck up to Waterton. We experienced much more wildlife in the Canadian park. In fact, that is where we saw this bear playing golf.
I'm excited to plan another trip to Waterton to explore a little more.