The scenery is spectacular and on a larger scale than Zion or Yellowstone. You will see rivers, streams waterfalls, great views and a few mountain goats.
Glacier is known for having a high density of grizzly bears.
Going to the Sun Road is still closed in May, check out NPS website for update, it closes again in late October. How to get there by air. The nearest airports are Kalispell and Great Falls. Kalispell is about 1 hour from West Glacier entrance. Bozeman is served by Delta and North West.