my previous car was offwhite... i put in some blue lights in the dash that made it looked nice as well as 2 neons under the dash. had a pioneer 7400 that had a blueish controls and displayed... when all the lights were on, it looked pretty nice imo, everything matched, except the minor ac lights, but that was very minor.
new car, black. id think red accents here and there look nice on black cars, like my friends rsx, i like how his interior is

. i guess thats why im shooting for a red headunit. but i could of course go back to all blue...