Here's something I came up with: combine a free-running CV sequencer with a free-running trigger sequencer, two sample-and-hold circuits, and two oscillators to create interesting duophonic melodies by just turning knobs. In my case I use a Xaoc Devices Moskwa CV sequencer for its quantized output, a Mutable Instruments Grids, a Joranalogue Select 2 for its low-droop S&H circuit, and two Shakmat Banshees. Additionally, I like to use the Doepfer A-173-1 mini-keyboard to transpose the second VCO (not shown in the patch).
The result is a melody that is sampled from the active CV step at every trigger, but since the triggers don't always arrive at the same time and the signal is held until the next trigger, both oscillators will often play different notes that are always musically related. Change the clock speed of the CV sequencer two influence which notes will be picked. Change its track length to determine how many notes to choose from. A variety of musical intervals, accidental chord progressions, and other happy accidents galore!