Bidets? No thanks. Heated seats? Don't need 'em. I think the smartest element on Japanese toilets is that some of them have a little faucet and sink on the lid of the tank; the water that fills the tank actually goes through that faucet first, then drains through the tank lid into the tank, so you can just wash your hands in that water rather than turning on the separate sink. An easy way to save water!
Granted, that water is damn cold in the winter…