Loving the tank man, I had the exact same fish stock as you, but then I got angels and it was all downhill from there, ate every single RCS lol, and some of the dwarf cories too. Good luck with your scape and stocking. +1 on thinking about rummynose school, they look really cool together.
I've been really thinking about what type of fishes I want in the tank. I'm probably getting a few more pygmy cories, around 5 or so. While I was at the lfs, I had my eye on some ember tetras. I thought it might look cool to have a large school, ~30 or so, of really tiny fish.