I've downloaded a few mods which enhances the New Vegas Strip. One is called The Strip Open which basically removes all the barriers in the Strip and adds a few aesthetic additions. The other one is called Populated Casinos which adds more people to the floors of the casinos. The next mod is called Living Casino Interiors, which adds people to the upper floors of the casinos.
I'm still looking for one that makes the streets more crowded with people. I'm also looking for one that adds more accessible casinos/hotels/buildings to fill the gaps between the few casinos in the Strip. Right now, the New Vegas streets look pretty empty.
I would love to be able to do this myself, but this well beyond my level!