Best way to power light circuit?
We had a single pole switch by the front door run to a J box in the basement and from there to coach lights on the front of garage. We never used the switch (always exited from garage), it was a 3-way on plans but not installed. So we stole that switch for new recessed lights on the porch, pulled the wire out of the box down to basement. I still have the 14/2 from the Jbox to the lights.
Now, we *did* have 2 3-way switches for the interior garage lights, one just inside the mudroom door and one just outside it. Always thought that was silly, so I replaced the 3-way in the garage with a single pole. The one in the garage was powered. The one in the mudroom that I would like to use for the coach lights is not powered, but it is in a box with the switch for the mudroom light.
I would *like* to keep all the garage lights (not openers, not receptacles, those are on separate circuits) on the same circuit. The box is pretty full, so I pulled the 14/3 out when I put in the new switch. I need a new Jbox to make the connection from mudroom switch to coach lights anyway since the mudroom (and the 14/3) is at the back of the garage. Probably don't have enough 14/2 on the coach lights to pull out of basement (even if I didn't tear it up - foam sealant in hole) so I was thinking of putting a J box above the existing garage switch box, where the 14/3 comes in from the house, running new 14/2 from the lights (unfinished garage - easy), and running power from the switch box up to the Jbox so the 2 sockets, 2 front coach and 1 back coach are on the same circuit.
Now, here's the rub - I have 14/3 to switch, don't need the white, was thinking of pigtailing in garage switch box to new Jbox to power the black on the 14/3 to the switch in the mudroom. Of course the white would be pigtailed to the white on the 14/2 going to the lights. Was thinking then I could use the red as the switch leg (would replace the 3-way with single pole) connected to black of the lights. But that means that the white in the 14/3 would not be used - I was a little afraid (for future work, any possible inspection) that capping it off would look like a mistake and someone would try to "correct" it by pigtailing with other whites. I can't really pull new wire - would be easy if 14/3 was stapled but I'm sure it is since the wire by the front door running straight down to basement was.
So, am I better off capping the white on the 14/3 on both ends, marking it on my plans, or should I cap the red and tape the white (which the electrician didn't do - argh, I should check all the 3-ways in the house!), use that one as the switch leg?
While I'm at it, would grabbing power from the "garage light" circuit as described above be preferable, or should I power the switch from the mudroom light (also kitchen lights, so I don't know if I'm at capacity already) just so someone looking in that box sees the neutrals tied together? Last option is to power the switch through the light (basement) by running power to the Jbox there but I really don't want to pull off a circuit there or run a new circuit just for 2 lights.
Looking for the least-confusing (to next owner/inspector) method w/o having to pull new wire from house to garage.