As for guitar playing plateaus, I highly recommend embracing alternate tunings as a shortcut / forcing function for adopting "beginner's mind", re-engaging your ear and your curiosity, and discovering new peaks to ascend.
A few of my favorites: - DADGAD (Black Mountain Side) - DADF#AD (Little Martha) - DGDGBE (Open G6) - CACGCE (Bron Yr Aur) - CGCGCD (Rain Song)