Interesting techniques! My biggest challenge with VCV Rack is to go from an essentially ‘steady state’ patch to a dynamic track. I’m getting better at it – coming up with patches that I can perform a mix with live – but this seems to work the best with techno or techno-like music where it’s OK to mostly do the same damn thing for the whole track.
Same. I feel like my patch design is getting pretty good, but I’ve yet to crack the code of turning a patch into a song/composition/whatever you want to call 4-5 minutes of interesting sound.
I mostly listen / make techno/techo-like music, but even with techno, the good stuff is always evolving/changing/moving. You can get away with more repetition, but I think you still need some movement.
Even if it’s not your main Genre, Try to make some ambient, since it’s slow and the sound is always in movement, you won’t feel repetition as much. Basic technique is to fade in voices as your track is going, maybe modulate some stuff by hand, just like you said, your objective will be to avoid too much repetition.
If your sound is static, then change notes from time to time, if your notes are always the same, then modulate the sound the most possible.
Try many techniques, genres, and in the end that will come naturally. Live performance and structure will become an habit as much as patch making 
I use asaf 8 and gridseq 64 to do this, though my sensibilities are not really subtle enough to do ambient.
It’s totally up to you what genre you prefer or are more confortable with 
but in my experience, i find ambient the less demanding and the ''easiest to sound good ‘’ one.
I’d love to make Techno or even maybe Synthwave in Rack someday, but i never managed to sound good in these genres yet 
Great tips!
I use these for ambient (discovered asaf thanks to vcp, thanks @ablaut!). Rampage / Floats are also good to move from pad to pad. My basic technique is to have several voices each with a different divided clock, where all the divisions are prime numbers (e.g., 5, 11, 17), so it’ll take a while until there’s a repeated combination (thank you, Brian Eno).
One neat trick is to store phrases in one sequencer and octave shift it with another (learned this from a rcm piano roll video); lets you get close to a Rapid Composer style keying in small repeated bits that can migrate over a chord.
Controlling sequencers with another sequencer tends to be fun. Maybe add some marbles/adrift down the line for subtle varieties.
I frequently use Bogaudio Stack to change key at various intervals. I’m pretty sure it was in an art of sound video from Nigel Sixsmith. I’m also sure that I have a video where I had both a generative key and melody line. Maybe one of the VCPs?