An option to opt out of, or into PvP
Speaking as one who enjoys PvE quite a bit, I would like the option, sort of like a PvP Queue so to speak, where one could enable their city or armies to be attacked or both. While I understand this is an MMO, sometimes I like to sit and micro my city and such without having to worry about a ever counting down protection timer or the looming of an attack.
In addition, I understand that alliances are coming soon and I think that were there to be some sort of co-op building or trading system that would be quite neat as well. For example, you ally with a friend and are able to add some of your buildings to his city and vice-vesa. I understand that might cause some balancing issues, but its just a suggestion. More interestingly, would be trade agreements between allied cities, as well as notifications that an allied city is being attacked, would you like to reinforce? Or for the attack, assist in the siege so that given all the possible locations of armies to spawn on one map, you could have 2-4 extra players with their troops on the map. Of course, if reinforcements are allowed, the attacker should get a notice stating that they will be facing a much larger enemy force, would they like to continue with the attack? etc. So that they aren't screwed upon arriving and what not.
Anyway, just my two-cents worth, thanks a bunch for reading.