Someone in a different forum on this site asked about the North Fork of the Flathead River. I've floated that river, and here are my observations about it.
In general, it is a Class II run. I launched at the end of the road, right at the Canadian Border. At that point, the river is gray with glacial silt, fast, and ice cold. Canadian mosquitos spill over the border, and they are as thick in the air as bad odors around an old outhouse.
The entire east bank of the river is Glacier National Park. In theory, you are supposed to have a back country permit to camp there. I was able to find good campsites on the west bank, so that was never an issue.
Grizzly bears are protected in Glacier Park, so there is guaranteed to be a population of them nearby. I doubt that they know to stay within the park boundaries, so they are probably around on both sides of the river. I never saw any on my trip.
I used my standard bear precautions: No food in or around tents. All food boxes and coolers stacked together and double-strapped. Pots and pans on top of the coolers, along with cups of ammonia. We had no trouble with camp-raiding animals of any kind.
The rapids on the trip are easy. My 8-year-old son rowed his own raft, and my wife rowed hers. The only spooky place was where a logjam extended out into the flow. The current swept right into and under the logjam. It was easy enough to row to the far side of the river and stay out of trouble, but still it is frightening to imagine what would happen if someone didn't recognize the hazard and ended up getting swept up against the logjam. Your lead boat needs to be in the hands of someone who can recognize such hazards in time to lead the group to a safe route.
We had a great trip, six days including a layover. We were able to do our own shuttle by leaving a car at the take-out, and the only trouble we had was when we got to the put-in and found our car there with a dead battery. AAA is a long way away! We had jumpers and were able to get it started.
I had a book, The Floaters Guide to Montana
, by Hank Fischer, which was some help in planning the trip. I don't know if it is possible to find the book today. Try www.half.com