I have a water damaged room I will soon be renovating. One thing I will do is replace the wiring (it is 30 years old), if for no other reason than because I can do it easily while the drywall is down. Now my question:

I know that code calls for 12/2 romex, but would I be wise to instead use 12/3, and simply cap off the red wire? My thought is that when I rewired my fire/CO alarms I used 12/3 and used the red wire as the signal wire. I am wondering if the third wire would be a useful for future expandability.

Note, these are 110 20 amp circuits, and I have no intention of changing that. My reason for asking about 12/3 wiring is the possibility that that third wire will be useful in the future for communication among smart devices and outlets.