The Raystown Branch has shown me some good days and I'd recommend it. It's smaller water than the main stem, with an average depth of maybe 1-2 feet. In my experience, it doesn't produce the large bass, over about 15," as consistently as the main stem but the numbers of fish are pretty good, esp if you can find a section with good cover and ledge rock and fish it under low light conditions. Based on my own rock rolling, RB seems to lack forage, at least in the areas I've fished it with very few crayfish and hellgrammites. With more forage it would be a fantastic river. It's also got a very good population of redbreast sunnies as well as some carp, rock bass, and tiger muskies. As for where to fish it, I usually fish further downstream than where you've been looking but access should be pretty good. Find a back country road with a bridge and check it out. At most of these places there is public access and the river is navigable so if you're within the high water mark you'll be fine.
Good luck.