I may have posted this before, I know I meant to but I don't see it anywhere.
After buying Pat Cloud's book 'The Key to Banjo,' I really felt like I was making progress on learning theory and scales and the general logic of the banjo. So when I saw he had another book I got that too.
Straight - Ahead Jazz for the Banjo is a lot more then a jazz book. He spends at least the first half of the book explaining string to string relationships, where minor 3rds, major 4ths, perfect 5ths lie on various strings. It's an approach that I've never seen before and it is working great for me.
Then he gets into exercises that are basically the circle of fourths in various chord forms and variations. This is by far the best way I have seen to learn the circle and the fretboard. I'm not even half way through the book and I already have learned more about notes and theory than I have in the last year.
This is a highly recommended book from a great player. I encourage you to check it out.
-Todd
On a side note for those Scruggs players I also found that learning some Bill Keith tunes will really help you too. The way he moves around the fingerboard ingrains the positions into your brain. And it's a lot of fun.