Roger on the 12 volt DC wall plug-in. I have resorted to using them for other DC only applications, mainly building flats that have LED light strips in them.
FWIW: I had been attempting to have one central power distribution hub - which is under my layout with numerous terminal strips, STAR wiring for DCS, all the transformers, TMCC/Legacy/TIUs, etc. From central hub, I began wiring in district terminal strips around the layout, e.g., one for industrial area, others for urban districts, etc., all AC voltage. As George mentioned, running 20-35 ft. runs of wire to power the districts is labor-intensive, but worth it.
The challenge is when DC voltage is needed and that's where the wall plug ins come in. The problem is then plugging them all in around the basement prior to having a night operating session; I thought the solution would be with Radio Shack controllers that turn on and off plug-in module units that plug into wall receptacles. However, when I go to control them, each RS module "trips" an internal breaker, despite total amperage draw being less than rating on the modules. I can only guess that the RS plug in things don't like AC-DC plug-ins, but that's a wild guess.
At this point, if I can get a building or tower to light it's a success; I've given up on the central control hub idea - that could be a retirement project 
