Well, I already had a detailed map of all the breakers in my panel,
detailing exactly what you suggest, down to the specific location of
outlets, whether they have any appliance or fixture plugged into them,
etc. Of course, I also have each breaker identified according to the
grid. Since reading your post, I've added the individual loads to the
master grid map I keep on paper (and my PC).

The experience I've had managing loads with this generator, when I ran
several extension power cords into the house, is that I preferred to
use the following circuits:

1. Below ground well pump
2. Above ground (house) pump
3. Refrigerator
4. TV outets
5. Computer outlets
6. One outlet in kitchen for 1 x 100W bulb on one small lamp (clip-on)
7. One outlet in master bedroom for 1 x 100W bulb on one nightstand
lamp
8. One outlet in another bedroom for 100W bulb on another nightstand
lamp
9. Two portable fans

The well pumps never presented a problem, for we scheduled all water
use for the same time period while avoiding use of other appliances at
same time. Of course, we avoided washing/drying clothes until after
power was restored.

I suffered for 12 days without power while using the above loads with
the current generator I have.

The main attraction of the interlock switch is that I can simply go
from room to room, or upstairs, etc., and simply turn off lights (or
appliances) in rooms not being used, then turning on needed lights (or
appliances) in the room breng occupied, etc. Being able to use the
overhead fans we have in each room is also attractive.

BTW, the lowest estimate I have received for a contractor to supply and
install a 6-circuit transfer switch was $600. One other contractor
quoted me 3 x that amount.