I'm sure many here are familiar with Mussorgsky's "Pictures at an Exhibition" having been introduced to it through Emerson, Lake and Palmer. There are two basic versions - the original piano suite and that suite orchestrated (by Ravel) for a full orchestra. And of course, our beloved ELP created their own masterpiece from it. Because what I'm going to suggest is playing electric bass along with a recording, the piano version works better than the orchestral version - there is no low frequency clash with the double basses. Not every electric bass guitarist is interested in classical music or playing his or her bass guitar along with a classical recording. If you are someone who's open to doing that, maybe for the first time - I have just the piece. "The Old Castle" is about 5 minutes into "Pictures", occurring after the second promenade. It is very unique in that its bassline remains on G# for the entire piece. You'll pick up the rhythm quickly - it's a slow 6/8 time. The payoff here is the amazing complexity of melody and harmony created over this simple G# pedal note. You can use any recording, but I would highly recommend the 'live' version (34 min) by Alice Sara Ott. She's brilliant. Link -
If you decide to take this on, you will be playing with one of Alice's left-hand fingers! Because of course, she has to keep that G# going. Again, it may surprise you, as it did me, the incredibly beautiful melodic and harmonic development happening here. Mussorgsky was a genius. Just tap that G# on your bass and sit back and listen to what's going on above you and that root note.