fbelec, I used 12/2 romex. Actually, it is a very good, secure, and safe install. For instance, I used all new wire nuts (including a new "Greenie") in the kitchen outlet. On the outlets, the wire was wrapped around the screws (2/3 - 3/4 of a wrap and in the proper direction) instead of using inserts on rear of outlet. Once the wires were connected, I wrapped electrician's tape around that part of the outlet to prevent even the possibility of a finger, tool, etc. touching the hot side of the receptacle.
When finished, the installation was tested with one of the typical plug-in circuit testers w/GFCI trip button. The chain of kitchen outlets tested okay, as did the bathroom outlet. As expected, when the kitchen GFCI is tripped all the outlets after that one, including the new bathroom outlet, trip properly. When the new bathroom outlet is tripped, only that outlet trips because there is no load attached to it.
Here is what I will have to do to run the new circuit: Drill a 5/8" hole through 18 floor joists, all of whose spaces are filled with insulation, domestic and outside water, heating and drain pipe. Then work in a very awkward position reaching over my Weil-Mclain boiler. All of this work will be from half way up a 6' step ladder. I must use a walker or cane when moving around the house so I am not a poster child for strength and stability while working from a ladder.
All kitchen receptacles and the new bath outlet work so well and the installation is so "clean" that I am tempted to leave well enough alone and not run the new circuit. There is a greater possibility of me being injured using the ladder than any damage or injury by stray current resulting from the new outlet. The cost of an arc fault circuit breaker for the new circuit must also be considered.
Your further comments will be much appreciated. John_M