Take a boat ride There is a smaller lake on the East side of the park, go take a short boat ride, then a short hike to a waterfall. Good friend from college drove that boat in the summer and lived in a little travel trailer behind the office. He got married on the Little Chief, beautiful old wooden boat, former rum runner that was shipped out from the East coast
They have open top cars, or did, that take you on a tour of the park. There is a lodge near the train station in East Glacier. If you do not stay there, at least go there and gawk at the awesome lobby of the place. There is or was, a little cafe in E Glacier that has excellent pie. Pretty sure you will not have huckleberry pie anywhere else than Montana, maybe Southern Alberta
https://www.glacierparkcollection.com/lodging/glacier-park-lodge/
If you are hiking take a whistle, blow it while you are walking along the trails, or put bells or your boots, something to make noise. If you see any small bears, go the other direction as fast as you can walk.
Take bicycles and ride up and down the Going to the Sun Road. There is a ranger station at the top that must be done by now