Using octaves is a useful way of reinforcing melody lines. When a melody is played simultaneously at different octaves; the ear interprets it as a single melodic voice. Octave lead playing stands out and is not that difficult to master. Any melody you know can be expanded to include octaves. The diagram below shows three octave pairs of the note C. All are movable and once grasped can be incorporated into your playing with ease. Wes Montgomery was a jazz guitarist who made octaves his trademark and his influence is heard in the work of the guitarist George Benson.
C major scale using Octaves