There are some GREAT recommendations on this thread. I'm definitely going to chase a few.
 
If you want to take a stretch and try a little Platonism mixed with mysticism (it's good for the right brain!) try this:
https://www.amazon.com/dp/0809128381/?tag=mh0b-20&hvadid=4960985170&hvqmt=e&hvbmt=be&hvdev=c&ref=pd_sl_9k9qw1wixc_e
 
It can be immensely complex at times, but with that complexity comes passages of soaring beauty. 

Jeff Evans
What you could also be doing is buy the CD Endless River by Pink Floyd and listen to it 10 times and come back and post in the Endless River thread here in Coffee House which everyone seems to be ignoring how bloody excellent it is. (Don't download or stream it either. The CD sounds very different!)
 
They all really know it but just refuse to admit it.   And hey with all the guitarists around here surely some of you should be reveling in the beautiful work that Dave Gilmour has done all over this CD.  It is a sheer masterclass in understated but very effective playing and his sound is just killer too in this.  Another serious lesson in what sort of lead guitar sound one could be aiming for.

So you like it then? 
 
I've always been a huge PF/Gilmour fan.  I'll check it out.