Well, crap.
I was buttoning everything up under the dash after all this gauge wiring stuff - and I even found the long-lost wire that goes to the switch on the emergency brake and plugged it up (it works!) and all of a sudden I noticed my dome/map lights weren't on anymore.
I'd been in and out of both doors dozens of times and I'm always mindful that they close enough to turn off the inside lights, too.
Fired the engine up and went thru all switches on the dash and everything else, including all the new gauge stuff, works fine. Instrument panel lights are fine, all lights/ flashers ok.
No idea what's happened here. Damn, ain't that how it goes?
I checked the fuse for dome light/cigar lighter circuit. It checked ok, looked fine.
I pulled the fuse box loose, checked out everything behind, verified 12V getting to the dome light circuit.
Both bulbs check good.
Both door switches looked ok when I pulled them out, too, although I didn't get any continuity or voltage at either. Is that right?
I'm trying to read the wiring diagram. What a mess.
I know my dimmer switch is new (and expensive!), but something is telling me to go in after it.
EDIT:
I'm an idiot. Chased this "problem" for hours today! Sheesh.
After having some dinner, taking a shower (it got to 100F here today and I was out in it for hours!) and passing out in my chair for a while, I woke up to the revelation that it might be a good idea to try the cigar lighter to see if it had power, since it's on the same circuit.
Tried it. Nope, no power.
Hmmm, I know 12V checks out as going to that circuit and I know the fuse checked out good for continuity...
I grab a pair of needlenose, climb up under that $%#$%^ dash one more time and jump the fuse with them....
....interior lights came right on.
Kindly disregard my stupidity.