Tetra plant substrate is cheap and pretty good, if you don't want anything too complicated. I've got cheap and easy plants like crypts and hygrophilia.
I want more fish but I have to get rid of my 180 litre if I want another baby but when I move to Canada I can have my own fish room I'm going to set up a river tank with hillstream loaches and a load of danios and have mega-fast flow from a load of powerheads.
All your tanks sound awesome.