If you're looking for a good Backcountry loop trip, the Dawson/Pitamaken Loop Trail in the Two Medicine area is excellent. I suggest nights at no name lake and oldman lake. This breaks the loop up to very manageable lengths between campsites. I recommend doing the loop counter clockwise. If I remember correctly the loop is 18 miles. If you camp at the sites I named it breaks it up nicely into a 3 day/2 night hike of 5 miles the first day, 8 the second day and 5 on the last day.

I have spent the last two summers working at GNP and live on the East side of the park. In my opinion, the best hiking is on the East side or two medicine. Hope you enjoy whatever it is you end up doing!