When I’m the one playing, I love the challenge of keeping the sound full, with just a bass and drums, and no chordal instruments playing accompaniment.
I see good rhythm guitar as a very high expression of a guitarists skill, but notice that the word “good” is italicized. There are some great examples of rhythm guitar out there, but there are some very poor examples of rhythm guitar, as well.Back in my journalist days, I asked Taj Mahal about this very thing, because he does such a fantastic job of it. And he was exceptionally nice about it, but basically found the question incomprehensible, because his approach is so divorced from the chord vs. melody idea. He apparently doesn't really even consider that. Just sees it all as accompaniment. I found that fascinating, since it's so out of the mainstream conception. But it totally works if you can let go of the "need" for backing.
On the other end of the spectrum: Django Reinhardt apparently got annoyed that Stephane Grappelli got three rhythm guitarists behind solos, and he only got two.
I see good rhythm guitar as a very high expression of a guitarists skill, but notice that the word “good” is italicized. There are some great examples of rhythm guitar out there, but there are some very poor examples of rhythm guitar, as well.
When I play rhythm guitar. I tend to use three different approaches. One if the classic Big Band approach, using three note chords, and remaining in the lower register. Think of this as the Freddie Green approach.
The flipside of this would be the chord-melody approach, usually using four-note chords in the upper registry, along the lines of a tenor guitar or tenor banjo. The melodic aspect of this doesn’t necessarily refer to vocal line, or lead guitar melody, but instead to the fact that the chord voicings can be chosen to form a counter melody in the upper registry. Wes Montgomery did a bit of this.
The third approach involves using triads, usually voiced on tne 2nd, 3rd and 4th strings. I like this approach, because it is crisp and uncluttered. The four flavors of triads, major, minor, augmented and diminished, can be used to represent just about any chord, providing that the bassist is covering the root and/or fifth, and moving the lower bass register in a logical manner.
With that as pretext, accompaniment is anything that supports the forward motion of the song. B.B. King’s single note accents have been criticized by some and put forth as evidence that he wasn’t all that skillful as a player, but I disagree. B. B. King was a very capable player and capable of playing complex melodic lines, but the accents he played were not meant as displays of melodic prowess, but were more along the lines of a chordal accent, reduced to a single note.
When arranging chord-melody solos of ballads (not to be confused with the chord-melody approach to rhythm which I mentioned above) the challenge reduces to availability of resources. There are only six strings, and sometimes you have time to fill for which there are few available resources. More than once, I’ve gotten out of a problem by playing a single note in the bass register to maintain continuity and flow, without adding clutter or abandoning the melody.
Accompaniment can work the same way, consisting of counter-melodies, arpeggios or accents. Another way is to lay down some simple sustained chords and adding single-note lines on top of these chords, which pretty much describes a keyboard part, and this somewhat circles back to the chord-melody approach to rhythm playing.
Basically, at the end of the day, if you advance the flow of the song, it will work, and that includes simply playing the melody over a bass line.