I am also a 3 tank keeper.

10 Gal, with a bristlenose plec and baby guppies
20Gal, white cloud mountain minnows, 1 guppy and some ottos
20Gal, 1 very hungry juvenille oscar. Marbled. (3 inch)

If I had a 4 foot tank, hmmmm

Probably some gouramis and a pair of angelfish, some angelfish proof tetras and cory cat fish.

Aquascaping, make own decorations from rocks and aquarium silicone and have lots of real plants.