#1
I'm going on a trip soon and am interested in a good theory book to bring along for the plane/downtime. Does anybody know of some good books that can teach me more about theory? something that relates specifically to the guitar would be nice. My current music theory knowledge is pretty average...I know some scales, chord formation, etc. Anything to do with the principles of jazz would be great. Please don't just point me toward a book full of scales, I'm more interested in concepts at this point.
#2
theory grade books are...

musicianship,

and music made easy.

they both go through levels and grades and are good.
#3
Mark Levine's Jazz Theory.
The "Popped Collar" Award(Sexiest)
Elvenkindje

The "Rest In Real Life" Award(Best Past MT Mod)
Elvenkindje
#4
IMO, you learn theory through application...so most likely you're not gonna absorb that theory. Well at least that's what would happen to me. And I would be thoroughly jet-lagged if I learned theory on a plane Maybe a book on music history? You can actually learn a lot of theory from just learning how music came to be the way it is. Like say a good book on how Jazz evolved instrumentally.

Oh actually, maybe a book on style analysis, functions of harmony, or some kind of treatise . That would be one of those things you can read on a plane...cuz it's just sit-down and read it kinda stuff. But I really think it will help you in understanding jazz too. Sorry if I wasn't too helpfull.
Gear:
Inflatable Guitar
Digitech GSP 2101/Mosvalve 962/Yamaha S412V
My Imagination