More island types and make some more common/rare then others (I.E. a rare "withered" biome where only monsters are.
More monsters (skeletons, slimes, anything really than just red, blue, and yellow wasps)
Water (Ponds, waterfalls from some islands)
Ivy/vines hanging from some islands.
More "decorative" things such as craftable flowerpots.
Love the game so far though, it looks amazing and is really fun dude!