Yep, pretty much it, though on principle its better to switch power to the solenoid rather than ground.
Don't forget the flywheel diode on that as well!
As Diver300 says, the reed switches are rather sensitive to spikes etc., sometimes even just from the wiring capacitance being suddenly discharged through the contact as they close, which is why it's a good idea to add the resistors near the switches to limit that current.
If you used a 24V relay, everything could run on the same supply?
Don't forget the flywheel diode on that as well!
As Diver300 says, the reed switches are rather sensitive to spikes etc., sometimes even just from the wiring capacitance being suddenly discharged through the contact as they close, which is why it's a good idea to add the resistors near the switches to limit that current.
If you used a 24V relay, everything could run on the same supply?