I've used simple push to make buttons for the individual roads, a DPDT switch for the turntable and another push to make for the turntable motor. I still use analogue, but when there's a few bob spare I'll invest in some decoders etc at some time in the future so all the roads can go live.

The small box used as a control panel is ugly, but I have to be able to get the model through the loft hatch for storage and I only just got about 3 feet to do it in. It works though!