I have LEDs in a couple of "add-in" gauges (my cars all have oil pressure & voltmeters fitted) but nowhere else - I had the dome light replacements fitted but took them out after a week or so - they were just way too bright & dazzling.
The LEDs in the gauges are custom built using single white 5050 SMDs - it was done to get a reasonable level of illumination - not so dim that they were unreadable (this was the problem with the supplied incandescent lamps), and not bright enough to dazzle (which is the problem with most of the commercially available LED lighting).