aaah yes... had to read your post different times before I understood what you mean

Now a little brainstorm, hope you can use it:

What about builder levels? So lets say a noob-lvl1 builder can claim a ... dunno 10x10 area. Placing blocks adds builder-XP. Lvl 2 is 15x15 and so on.
To claim a area you have to get these 'claimflags'. These are quite expensive to get (e.g. by rare matierals etc.) After claiming 3 different areas and leveling up to builder lvl 10 e.g. you can claim quite big areas and invite others to build with you, so you can found a village. If your village has some specs (inhabitants, farms whatever) you can claim an additional district to your village, so its a town. After growing again you can claim district nr3 and the town becomes a city.
I would love to see some transport systems. Like if your village/town/city is connected to a street it gets bonuses, same for the sea and so on. You should be able to give certain buildings certain roles. Like a store, city hall, dock etc. These buildings have to fulfill certain specs, too. A dock has to be partly in the water and at least 5x10 blocks or whatever. Having more and more buildings with these roles you get bonuses again.

Now let the tourists come! What about a 'LikeBox' for a town? Every player gets one Award Coin every week or so. So the player can put that coin into a LikeBox of a settlement if he likes it, but NOT at his own village! So you ensure to get not only funktional but good looking and innovative settlements cause these coins give bonuses, too. And usually people do not like ugly stuff.

Settlements bigger then 3 districts, a metropolis, have to be unlocked by a admin of the server. That prevents the huge stuff being build without admin permission and spamming his server. These can have like 5 districts and have some special bonuses (inner-city transportation system or anything else whats cool )

.... thats it for now, do what you want with my ideas