I think a quadrature rotary encoder with a push button is a very nice and intuitive user interface. Turn encoder to see function options available and press switch to select it. However as others have said a quality rotary encoders seem to be costly and the cheap mechanical one I got is not very precise in it's detents Vs steps.
I read one article about converting a stepping motor to act like a rotary encoder. It required a little external components but sounded like a need project to play with. Some steppers have very nice feeling 'jogs' and with a nice heavy knob might have a very nice feel.
Lefty