For guitar, with my styles, I definitely need more than "one stop shopping". Most of my guitar playing nowadays are super de-tuned metal (crust/grind/dbeat/powerviolence stuff) so I mostly surf
www.sevenstring.org. But I also frequent TDPRI for advice and have an account on the acousticguitarforum.com. Those are probably the best three that aren't full of douchebags.
For drums I like the section at sevenstring.org and the pearl drum forums. But I'm not a huge drummer and just dabble on it on the side.
I sort of wish Talkbass would just add a few separated forums like
"Guitar/stringed instruments----"
"Drums/percussion------"
and so forth. Maybe just under the Miscellaneous section. As much as I value other forums, I value the knowledge people have on Talkbass the most and would much rather "talk shop" with everyone here.