I set my main bench just as Martin says. I then set the lathe & drilling machine bench, which buts up to the main bench to the same height thinking that I could then slide stuff from one bench to the other. That never happened, but what did happen was that once the lathe was set up with adjustable feet, I had to use a 110mm step-up in order to use the lathe comfortably. The drilling machine was satisfactory until I extended its column vertically by 100mm: I now occasionally have to use the step-up.
Height of top of vice jaws above bench top: 175mm,
Height of lathe cross-slide top above bench top: 235mm
Height of centre of drilling mean quill handle: 525mm.
The milling machine is, by accident, set slightly lower than the other two benches. The machine stands on 48mm spacers to allow the Y axis handle to be easily used. The table top is 185mm above the bench top.
Regards,
Peter G. Shaw