I reinstalled New Vegas recently just to give the New Vegas Reloaded graphics mod a go. It adds proper shadows and a bunch of other visual tweaks, all optionals, to the game.
Unfortunately the game still looks pretty bad because of the vanilla weathers, and the modern weather mods don't really look that good to me, they are all a hit or miss.
In the end, I think I may have played New Vegas far too many times already. You know how there are movies you have watched 20 times and every time still feels like the first time? New Vegas no longer feels like that to me.
I tried to fill the void with Fallout 4, but ugh. It manages to feel like New Vegas in that I get boring very quickly, in spite of how much "stuff" (shooting enemies and "exploring" shooting galleries) there is to do. But it's probably the awful writing that kills the whole game for me, I feel not an ounce of empathy for its cast of NPCs.