My wife and I just backpacked the Selway from Race Creek to the Ranger Station at Moose Creek a couple weeks ago. Only had 4 days, as we had to be back for our daughter's dance recital. Here are a couple observations for anyone considering that area:
1. It's actually 25 miles one way, not the 22 often referenced on maps. At least that's what my GPS tracked. We ended up doing close to 55 miles in the 4 days including a bit of off trail exploring.
2. The trail is NOT "river grade". It was about 9000 ft of elevation gain and 9000 ft of loss over the 50 miles round trip to Moose Creek.
3. If you are there before the runoff takes off, you can avoid getting your feet wet crossing the 20 or so feeder streams along the route. But once temps are consistently in the 70s each afternoon, the streams get full and rock hopping or log crossing becomes sketchy at best. Some have legit bridges... but not all.
4. Finding campsites is a serious problem. There are fewer than 10 quality camp sites along the whole route. Early season there is no permit required for kayakers who can get transport to Paradise over Nez Perce Pass (guide companies have modified vehicles that can travel over the snow pack) so there can be multiple groups on the river, the ones we talked to would typically take 2-3 nights to do the whole stretch, which means they will be occupying some of the campsites. Later in the season, only one raft/kayak group is allowed on the river at Paradise each day.
The parking lot was full when we were there, with an outfitter taking up the upper portion of the parking area. Outfitter or hunter stock camps filled up most of the other available camp sites along the route. I would assume the congestion only gets worse the further into May you go.
However, there is plenty of camping on the side of the Airstrip st Moose Creek. Only issue is that there is no water there... so it either requires a hike back down to the river or a hike up to the spigot at the ranger station.
5. Very few of the side trails that show up on the map are regularly maintained, which means that for many of them you might as well be off trail with the amount of dead fall that covers them in a season or two.
6. I've never seen so much wolf scat in my life! I swear you can't go a hundred yards without stepping on some.
7. The trail gets used heavily by mule and other pack strings. While we were there, the forest service packer was hauling in a load of wood shingles to rebuild the roof of one of the cabins at Moose Creek. Nearly 20 mules in the train. Pack Stock has the right of way on trails, and there are plenty of sections of the trail that are 600 feet above the river with cliffs above you and below you... and barely room for a mule... and zero room for you and a mule. Be prepared to have to backtrack down the trail a long ways until you find a wide enough spot to safely let the mule string to pass. Also note that if there has been any recent rain, the pack strings churn up the trail to a muddy mess. There are stretches where you will be slogging through ankle deep muck for a mile or two.
8. There are places to glass, but most of what you can see from the trail is across the river. Most of the route is too steep and thick on your side of the river to glass much at all, unless you climb up a couple thousand feet above the river. I could see hauling in a pack raft to get across the river at calmer stretches... but that's a lot of extra weight and space in a pack if you are on foot 15 miles in...
9. I spoke to a pilot at the Airstrip who has been flying in since the 70s, and he said he has never killed a bear before May 1 in there. We did see a few bears... one small boar across the river, and a sow and cub about 3000 ft above the river in the cliffs on our side. I think that a popular approach is to fly in to Moose Creek... but then you have the serious logistical issue of what to do with your meat and hide if you kill a bear on day 2 of 9 and you've still got other buddies who want to stay and fill their own tags. It gets HOT in the Selway in May and June. Guys who were in there last week were saying it had been in the 80s for several days straight... not great for keeping meat fresh.
10. It's beautiful country, as is much of our fine state of Idaho. However, I think there are far less crowded areas to find a bear in Idaho, which will have equally high bear densities and far fewer logistical issues to make a quality back country hunt.