I have the back and quarters tinted almost black. That's one of the first things I got done to my car. I MUST have my windows tinted. Cant tint the sides though in Cali. I think you could get away with a very light smoke. I think that and rims add a world of difference to a stock stang. The tint is probly like 9 years old and is holding up fairly well... they corner is peeling a bit and bubbling but over all in good condition after so long.
(thats an old pic.. probly when I first got them tinted..)