I want to use the corresponding switch to light one of two leds, and sound a buzzer. In order to share the buzzer between the two switches, it became apparent that I would have to use diodes to isolate the switches to ensure that both Leds do not light when a single switch is thrown. It seemed to work. Is this an acceptable approach? Any potential problems? Does the diode consume much power? See schematic

 

Using diodes for that purpose is standard practice.

The only possible problem is that you lose about 0.7V drop in voltage across the buzzer from the diode forward voltage drop.
If the buzzer is adequately loud, then that's not a concern.

 

The diode which is conducting current will convert approximately 0.7 volts x (buzzer current in amps) into heat.
P = IE
Power = current times voltage
And yes, diode logic is the usual way to do this in a DC circuit.

 

Thanks guys ... seems to be working fine.