Q: Any general tips for writing parts for two chord-playing instruments (like piano & guitar, or 2 guitars)?
A: that's kind of a trick question because often when writing for those 2 instruments you might want 1 to play chords and the other not. but if they are both playing chords they should be playing the same chords. at least the core of the harmony should be the same, and most importantly in the same octave. they will blend nicely together