I have been waiting so long for someone to ask this. Well, my ideal server would be three cities/towns/civilizations that each have one pre-made faction (players cannot make factions, and they don't have to be invited) and each city is built in pure vanilla mode, by the townspeople. Each city can also trade resources, or have war with each other. There is no grief protection, except for a 50 block radius around spawn. There are absolutely no plugins for this server other than the factions/clan/groups plugin and Essentials (sethome, tpa, msg)
The currency in this server is some kind of material, preferably gold nuggets (please no Economy Plugin, everyone hates it). I have a lot more ideas, but I couldn't list them all here, so please message me for more information.