I don't think I would delete them on an impala. Maybe on a caprice though. The Roady's and fleetwoods don't have quarter windows and I happen to be rather partial to how they look. You need something there though, like the opera lights on the roady or it looks kind of strange. I think it would be easier to just keep them though and spend that time/money on other things like LSx swaps
Edit: for what it would look like, just look at a BBB with heavily tinted windows. It is close enough to what it would look like with that window replaced with a body coloured panel...
unlike the roadmaster thats square and doesnt have the quarter window. the impala/ caprice has curves and is rounded. that quarter window makes a big visual difference. all mods arnt good! deleating the the quarter glass would be a horrible thing to do mush less a horrible idea. DONT DO IT.
A friend of mine Frank Varela done this to his 91 Caprice about 8 years ago. I welded a piece of metal in there and finished smooth with bondo.
It did not look too bad, it was different.
Frank is into square cars, like '80 caddy and Lincoln Mark 5.
if someone digs luxury cars it's not so bad.
i didn't care for it, since i like slick sporty look.
So, 1/4 delete,skirts,wire wheels and Rolls Royce grill for some and 95-96 1/4, open rear wheel and no chrome for others.
I think its been done a time or two. It looks kinda weird as in the photoshops above. It reminds me of guys with mini trucks that fill the rear side windows. Shaving stuff off is cool but that one I wouldn't do.