I recently unearthed this little volume on my shelves and read it again out of pure nostalgia - I actually walked the King Ludwig Way, about 15 years ago now maybe? And this was the guidebook I used to do it. Very clear and useful, and it helps me remember the various places along the track really well.

It's a fantastic walk, if you get the chance you should do it (the highlight, apart from the castle, was the beer at Andechs Abbey). You could do a lot worse than this pocket-sized guide to see you on your way.