In a typical season, its possible to get a decent 2-4 night walk in permit if you don't mind getting in line early in the morning. Considering many people will not be interested in going to Glacier without an advanced reservation permit, it could be a great year to get good walk in permits. I am unsure if the campsites not used for advanced reservations will be released for walk in permits but that could also increase the chances of getting a good itinerary.
Thoughts?