I'm well aware it'll never happen, but I think it would be kinda cool if they DID go George Lucas insane on TNG - but as an optional extra with the original versions, of course. I'd love to see them walking past far more alien crewmembers (like the kinds seen in TAS, TMP, STIV and ST) in the corridors and manning the consoles at the back of the bridge.
And the biggest nit I'd fix is seeing the rear of the ship outside the observation deck windows, and maybe seeing the curve of the saucer at the bottom of the viewscreen. I've always loved shots that connect the inside and outside of the ship. It would really add a sense of scale.