Highline trail is one of my favorite hikes in Glacier!! There are two ways you can do this hike - you can either treat it as an out and back trail (7.6 miles one way, 15.2 miles if you do the whole thing), or you can do the loop (11.8 miles total), but you'll have to take the free shuttle back to the trailhead at Logan Pass. Since the loop ends at The Loop Parking lot, you could also park here so your car is waiting for you and take the free shuttle to Logan Pass to begin the hike!
We saw lots of wildlife on this hike and it ended up being one of our favorite hikes in the park! If you're scared of heights, the path can be a bit narrow and it's a steep drop off! Not to worry anyone, we didn't think it was too bad but it's better to be prepared:)
Also, if you don't want to do the full hike, you don't have to go far before it's absolutely gorgeous, and it stays that way the whole hike! You could always go in a couple miles and then turn around, the hike doesn't have significant elevation gain or loss unless you're doing the loop.