A major point of interest is going to be the Missouri Breaks National Backcountry Byway. It's a 80 mile loop off of Highway 191 between Malta and Lewistown. The book boasts about the spectacular scenery along the Missouri River... and also warns about the need for a 4 wheel drive and/or high-clearance vehicle.
To date, this sounds like one of the better roads to travel. A good place to kill an afternoon.
Outside of the information in the book, I'm finding little to no real good information about this route online. Mostly just what the BLM sites have available... which isn't a whole lot.
Missouri Breaks Backcountry Byway
I'm still trying to find out also whether or not the road that goes to Kintla Lake... North Fork Road, I believe it's called... continues on into Canada. Which also makes me wonder if there are gates or manned posts at the border. It'd be cool if we could cross into Canada... just to say I've been in Canada before. :oP