Pluto, Charon, Nix and Hydra all have an abundance of water and nitrogen ice. However, these dwarf planets will get poor solar energy due to the distance from the sun. Due to the extremely weak gravity, it would be nice to have artificial gravity so people who inhabit these worlds will not be physically weak or have major health issues. This gravity might be provided by hollowing out these planetoids and increasing their rate of rotation. People would live on the inside.