try shaping the bottoms of the islands (using worldedit). you want something that looks natural. the shape you have right now resembles that of a modern city. make the base of the islands first, then building on top of it. since you seem to be going for a desert theme, i would highly recommend making something that looks like an ancient ruin/temple. stay away from making perfectly symmetrical pyramids too. you could also place a couple palm trees and shrubbery around to give it more color.
i have try different things, like sharping the bottom island, but it will look like a beard which does not look good. so this point i have already considered and veto.
making things like ancient ruin/ temple. this actually is a great idea if you meaning this to be built in mid, but later will found that the pvp space will be small especially you have to build a rooftop for the temple/ ruin and looks too crowd. so that wont be a great things for player.
Adding trees in the map is the greatest idea i think, i will try it out and give a video reply for u!
Thx for your advice anyway!
