@kevin1. Agreed, I put a CT (DCM) on the furnace breaker, and even when the blower motor is off, it’s showing a standby power of 17W. I think this is for both the furnace’s logic board and the thermostats, as those are fed off furnace’s line. The plan is as follows:
Step 1 - Identify how much each circuit draws (always-on) by simply using the live monitor and toggling each of the breakers in the panel box., then reading the delta.
Step 2 - Once specific rooms/circuits (with highest always-on) have been identified, go in there with a traveling smart plug (as you said) , and ‘measure’ how much each of the local devices draws power.
It’s a lengthy procedure, but certainly will give a good picture as to where each Watt goes.