I don't think having multiple "villages" within a huge region would be very effective, for the reasons Pyrocide laid out above, but I do think it is possible to create a similar effect.
Even the most dedicated of city-lovers will, in time, desire to own their own city, mansion, or "expensive" build one day; it's the nature of Minecraft to upgrade.
So, building on Jeroxia's comment about mansions, why not just have a bunch of private estates and large, independently-owned farms pop up around the countryside? That would give spice to the surrounding area without creating "competition" in the form of new villages.
You could also build ruins of cities and builds to fill up space in the surrounding area; no one would live there (except maybe a caravan merchant or two
), but it would still provide a host of new places to explore and create RP in.
Also, going back to the rails-systems, I actually did have an awesome idea for a dwarven rails-system involving a broken bridge and "accidental" drop-off onto a lower (100m+) "mine shaft" rails-system, just in case anyone was wondering how to make an interesting RP minecart adventure...