I've noticed in this type of game, it seems like there are always roughly 2 types of players: The player killers/Warmongers, and the resource builders....
The warmongers always hunt down and raid other players (normally dominating the game), and the resource builders just want to build their little community and be left alone. I think that an interesting feature to add would be to allow players to become mercenaries, hiring out their services for X number of days of protection in return for money or resources....
...anyway, just a suggestion for when the PVP becomes active. The other option would be to allow for kingdoms, and for players to come under the protection of a king, and pay tribute (and get protection). This would also open up the possibility of revolutions and other interesting quest ideas....