Ppl might hammer you for not being specific enough fyi, but to answer your question sort of, the lower the divergence, the longer the throw. The throw can be increased even further with a beam expander. Google first
Actually, you don't really need really a powerful laser. Even an average green will be visible on targets a long distance away if you look hard enough. It may not be as good as a laser with a beam expander, but it'll go a pretty good distance.
I understand what you mean when green is the most sensitive, but if you compared a red and green laser dot, which color would come out clearer, regardless of brightness? That's why blue and violet lasers lose sharpness in the visibility, ending up more blurry.