Just what it says; if you’re a reasonably experienced backpacker and/or packrafter, and want to do one trip in the Bob Marshall, the following are my current recommendations. One suggestion each, for hiking and packrafting. Good loops are possible, especially for rafting, and car shuttles around the Bob are long with almost no commercial options extent, but a traverse is simply a better experience. It is worth the hassle.
Start at the Lion Creek TH, near Condon in the Swan Valley. This is an easy 3.5 mile drive from the highway, with no cell service. Lion Creek has exceptional old growth forest and waterfalls, Lion Creek Pass great sub-alpine scenery, and Palisade and Little Salmon Creek good walking on a relatively infrequently used trail. One of the challenges inherent to hiking in the Bob is avoiding, as much as possible, the well-used (trashed) horse paths, which are usually unpleasant. After you reach the South Fork head upstream to the White River. Below 2000 cfs there are plenty of good fords in this stretch, much above 3000 and a detour up to Big Prairie and the bridge is recommended.
The White River makes for great walking, while the trail up to Haystack is a steep grind with little shade. The traverse across the top of the Chinese Wall north to Larch Hill pass, is spectacular and challenging, with limited water sources, especially later in the summer.
Larch Hill pass also provides big views, while the miles down Rock Creek to Gates Park is relatively innocuous forest. The miles up the Sun River, and then up Route and Nesbit Creeks to Olney Creek, are fast, with a mix of forest and big views. The same can be said of the North Fork of the Teton, before Phone Creek and the massive limestone formations of Birch Creek and Swift Reservoir. The Swift Reservoir campground and trailhead is a pleasant end to a long trip, right on the edge of the prairie. This isn’t a route for the worst view-whores, it has plenty of big scenery but the chief virtue is a subtle and ever-evolving showcase of the tremendous variability found in the Bob.
The main logistical challenge of this route is going late enough to not have the detour up to Big Prairie, while being early enough to have water up on the Chinese Wall. The best strategy is either to go in early July and do the detour, or to go in September when temps are cooler and hauling water up to Haystack is not so obnoxious. Fast folks will do this route in five days, many will want twice that.
I still think the pinnacle packrafting experience in the Bob is to float both the South and Middle Forks of the Flathead in one trip; something I myself have not yet done. The trick here is having enough water (>2000 cfs) in the upper reaches of the South Fork, while not having too much (<4000 cfs) in the lower Middle Fork. When this most likely to occur varies quite a bit year by year, but late July is probably the best bet.
Youngs Creek is my favorite run in the Bob, but the bikes into Youngs are on major horse trails and thus less than ideal. Hiking up Monture Creek and using Limestone Pass to access Danaher Meadows, on the other hand, is sublime in many contrasting ways. If you’re a conservative boater and trying to hit the Middle Fork at the lowest level that will still allow passage on the upper South Fork, Danaher Creek might be too low, in which case switching to Youngs Pass and Creek makes sense.
After floating the South Fork to Mid Creek, hike up Mid and over into Silvertip Creek. Camping on the ridge is recommended. A ford of the Spotted Bear River and another ridge hop up Dean Ridge and Gunsight Peak puts you down on the Middle Fork in Schafer Meadows. The first few miles will be slow, but the whitewater will soon pick up. Tentative boaters will probably want to walk down to Lodgepole Creek before putting in, and portage the whole Spruce Park section.
Trip time will depend heavily on water levels and how often you stop to fish, but again five days is the minimum short of race pace, and it would be easy to take twice that long.