My only gripe with Rings from a distance is that they often look absolutely regular, symmetric and perfect... like a record holding 100 identical tracks that repeat accurately.
I also wouldn't mind seeing them volumetric to some extent. Currently they're a flat pixel line when viewed from the side, indicating no Asteroid Ring in the entire Galaxy has a higher Y-spread than about ~10km.
How they look from the inside has been discussed very often after the GFX downgrades, it leaves tons of room for tweaks and improvement.
Icing on the cake would be some physics. Bumping them around and having to take care not to get caught inbetween two that just happen to move

(just something dynamic within the local instance, something that gives a little challenge or plain visual entertainment flying inside them)