485 is just a physical layer - protocol is up to you - also lots of driver chips available, dual and quad packages too. Its fairly power hungry though using full-swing differential signals into 100 ohm loads, a LVDS chipset would improve on that markedly.
For low signalling speeds serial is still attractive, but long runs could introduce problems with mismatched grounds. If you low-pass filter and then schmitt-trigger you can clean up a lot of noise pick up if only needing low baud rates.