I don't have any AI on. Have had no traders visit my island yet
Do you specialise each island into a particular role e.g. making weapons, or have a mix on each? Should there be an island just for housing, or should every island have houses?
If you want a peaceful game, you should still have at least the basic three Ark characters on. They won't settle islands or attack you, but will trade with you and give you quests.
I still havn't gotten end-game on 2070 yet, but in 1404 I would have two islands with housing (One for each faction) with the only non-housing being the buildings that were gathering raw materials on that island.
During the mid-game in 1404 I would typically have one or two other islands settled with 75 peasant houses, 3 fish huts and 2 cider farms each which would net 700-800 gold each and acted as a nice income buffer when teching up.
In 1404 my end game would involve having a buffer island that would produce basic building materials (Wood, tools) and finish the chains for other building materials (Glass etc), and would be storage for pretty much everything. In the early/mid-game I would have full production chains on an island, but late game I would have islands simply producing their raw mats and shipping them here, to be shipped to a pure production island to finish off, before being shipped back and then shipped where they were needed.
I'm not yet sure how this will work in 2070, although I actually really like how there are now buildings that are not required by populace, but require populace themselves. I will probably strive to have an end-game of two populated islands, but I don't know what they will contain. I've chosen Tycoons so definitely one Tycoon island but I don't know if the other will be purely Techs, or Techs and Ecos or even if I could get away with a seperate island for Ecos.
As oxygene said above, trying to balance consumables across several islands is very, very difficult when it's with one faction. It's not hard when the other island is a different faction as they have different needs.