I'd go with red interior with a black exterior
I actually like your grey under black interior leapy, (in the blue car on the photo you use) though I might go with a shade or two darker on the light color. (I would call it maybe a titanium grey. My 2001 is currently stock red exterior, charcoal interior.)
I would want to do that for the door and seat inserts as well as some floor mats, and then try to match across the dash and console surfaces to that color. I could find a dark looking "marbled" (grey/black swirl) formica type material for the center control console surfaces, cut it to shape . . .
The trouble is getting the flow of color to match across all the tid bits in the car . . . (I could do it, but to do a really good custom leather seat cover would go for almost $1k per, a more OEM gear knob could be $3-500. and then if the color doesn't want to stick to the underlying material on the odd bits you have to paint or dye . . . it could look pretty bad in short order. :-( Sort of rough to spend $10k customizing the interior of a car only worth $10k at the start.
A possible way to do the door trim panel inserts would be to get with a friend who wanted the opposite color combination and then buy two sets of panels, one each color, (say one red and one charcoal) and then swap the inserts, handles, etc. . . . Everything would be "stock" then. I can't find a lighter grey unfortunately. (I would entertain red inserts - Though I wouldn't want to extend the red onto the dash. :-( I do need to replace my drivers side panel (about $700 new - previous owner abused the arm rest mounting) so I might try a few things with my old panel if I do that . . .
>> Added color swatch - I might try this on my current door panel (which is about to have the insert fall off) with some paint from Colorbond. <<