Anyone who has ever completed the Bear Lake to Grand Lake trail over the divide could not have missed North Inlet creek. The convenient trail follows the creek. This is one of the bigger drainages in the park. You would want to hike in over Flattop Mountain from Bear Lake and camp at the put in or hike upstream to see if you can find a gorge. There are some big falls on the way to Grand Lake I can recall jumping off of, though it's all relative considering I was 12 the last time I did the Bear to Grand trail. Could be a long, woody class IV.
There's other stuff back there. For East Inlet hike up from west portal, there are some falls, this creek drains the west slope of the park's most southerly 13ers, Mt. Alice and Mt Isolation, down to the boundary with the Indian Peaks.
I would be very curious to hear reports of any boaters getting on Glacier with some water. Despite TG's claims of not worth running I beg to differ. Having been down the whole thing years ago I can still remember the potential in there with some more water.
Anyone ever been into Forest Canyon?