I've been playing guitar for 37 years now, and collecting books and videos on the subject for nearly as long. With the advent of eBay, I've been able to go back and re-buy relics from my formative years - old Mel Bay chord books, Pat Thrall's "Improvising Rock Guitar ( an early attempt at teaching Rock), and even earlier kitschy volumes like Ed Sale's "The Guitarists' Book of Knowledge". I have a nice collection and from time to time I thin it out with loaners or giveaways to friends and family.
The other day a friend stopped by to help re-configure my studio computer and was asking if I had anything he could work on to get him out of a rut. He's a hobby guitarist who played enough to get decent and now wants to learn more. Everything he knows he figured out by ear, at random moments in time. Without an overall approach or method, he has gaps in is knowledge that frustrate him and while he can HEAR what he wants to play, he does not always know where it is on the neck.
I gave him my copy of Bill Edwards' "Fretboard Logic", a modern take on the classic CAGED system. I think my first exposure to it was a 1986 Guitar Player magazine article with Joe Pass. This approach to organizing the fretboard was news to him and after a few minutes of demonstration, light bulbs were popping and it was great to see and hear his enthusiasm. It was like he finally had a set of keys to ALL of the closed doors.
The great thing about the CAGED method is that it is style-free. It does not matter if you are playing Classic Rock, Jazz or Hip-Hop, the method applies. There are tons of YouTube videos exploring this concept, in addition to the video series at Guitar.com. Once you start to see the spatial and harmonic relationships - and the differences - the style of music does not matter... only the Music.