Songs difficult to learn on my Thunderbird/Embassies (since that's all I play these days):
I agree, Rock and Roll Hoochie Koo, even the Johnny Winters version, lots of tasty bass runs and 3 octave shifts
Simple Man, I had to chart it out, over 18 variations of the basic pattern (the bass part was played by Ed King, so approached with a lead guitarist mentality, an approach I have no experience with since I've played bass since day 1 in 1968). I Ain't The One a little problematic, but more technical than because of numerous changes.
Believe it or not, Born On The Bayou by Creedence, lots of small variations throughout the 5 minutes.
Being in a 3 piece band, the bassline has to be solid and indisputable or doubt creeps in to the band mindset, never a good look. This is complicated by breaking in a new drummer.
Sorry for the self indulgence.... not easy to relearn 40+ songs these days