The Highline Trail in Glacier National Park is an amazing hike featuring beautiful views that is a great physical challenge due to the distance alone.
Starting at the top of Logan Pass at the visitor's center, walk across the street to the well marked Highline Loop Trailhead. This is written as an out-and-back hike, where you will simply hike back to where you started from. However, if you'd like to catch a ride back to the trailhead, check out this adventure: Granite Park Chalet via the Highline Trail. Keep in mind, if hiking one-way, you will need to have two cars or make use of the shuttles in order to do the hike. If you have two cars, park the second on your way up Logan Pass at the well marked parking lot called "The Loop" then pile in your other vehicle and continue up to the trailhead. If you plan on using the shuttle, be sure to check out the Glacier National Park website for information about stops and schedule.
The trail takes you along a ridge for a good majority of the hike starting at about 6,500 ft, peaking around 7,200 ft, and ending at 4,000 ft. Many switchbacks that lead into meadows filled with wildflowers and magnificent views. Around 8 miles into the trail I suggest walking the short detour to the Granite Peak Chalet which is a great place to eat your lunch. Keep an eye out for mountain goats and bighorn sheep, they are all over! This hike is mostly exposed so I can't stress the need for bringing enough water and sun protection.
To get to the trailhead from Whitefish, MT, leave town heading east on Hwy 2 and drive for about ten miles. Make a left at Going to the Sun Rd. (closed during the winter) and follow for about 45 miles until you reach the trailhead at Logan Pass.