All I meant was that I ignored the LED voltage drop in the resistor calculations that I posted because I didn't know which LED you were using.
Different color LEDs have different forward voltage drops. A white LED could have a 3.5V drop where as a red one maybe 2V drop. So, for a red LED (2V) and a 1.2K resistor with a 24V supply, you would get (24-2)/1200 = 18.3ma current. If it was a white LED (3.5V) and a 1.2K resistor with a 24V supply, you would get (24-3.5)/1200 = 17.1ma current. You are not going to notice the difference of 1ma in LED current anyway and both values are within the spec of most LEDs.
BTW, I would go with the lowest supply voltage that is convenient, to minimize power dissipation in the LED dropping resistors.