In my opinion there is nothing wrong with neons as long as they're not ghetto rigged. If you know what you're doing and you wire/hide them correctly, and they don't do gay flashes/ pulse to music etc..
Neons have been given a bad name (like most other things) by the world of rice. I remember when some of the first underglow came out and everyone was going crazy for it.
I say if you like them, put them on your car just do it
right. Don't go overkill with tons of lights on your car, my room-mate has a stupid civic with like 25 leds in the front, underglow, lights in the interior etc etc and needless to say it looks like shit.
And as far as the 'best' color for silver, there's not much that doesn't work with silver. Just be careful with red/blue because they are considered 'emergency' colors. Just do what you like.
