disconnect fan on switch at t-stat.

I own a Bed and Breakfast Inn with 7 rooms on a zoned forced air HVAC system. Occasionally a guest will set the t-stat to fan on which can alter the comfort of guests in other rooms. I would like to be able to disconnect the fan on switch on the t-stat so that it is always in Auto mode. Currently I have some old round Honeywell stats and some digital stats. I have no interest in programmable as that would just further confuse the average adult. Any suggestions or advice?

disconnect fan on switch at t-stat.