Yeah a better cities mid would defenatley be nice.
But I don't really see a need for new models, like the eifel tower. I think just adding a lot of clutter, houses and shacks, markets etc would do a great deal for the game.
Creating scenarios would also be great, things placed in a way that you could imagine what had happened.
Better Cities was really good for OB and if someone decided to make this for NV they shoul defenatley at least take a look at what kind of changes where made in the OB verision, because that really did the job adding a lot of feeling to towns.
The most important thing I would say is to stay true to cities setting and history. Making freeside into much more of a slum and the Strip into much more of a luxury place for example. Right now The Strip only feel like huge empty streets with shiny buildings next to them, I would like to see more stuff that makes the streets a bit more alive.