How about more decoration blocks such as Aether Bricks? You can now find new Heavenly Clay which can be smelted into an Aether Brick. Aether Bricks are basically just like regular bricks but a light blue color. You can make special Aether Flower Pots (Which have Aether Dirt in them, instead of regular dirt. This makes it so that you can only plant aether plants in Aether Flower Pots.) and Aether Brick blocks. Maybe a new ore could be added, too? Aether Quartz. Aether Quartz is just like Nether Quartz but has a dark blue color like lapis lazuli.
Maybe some new weopon types? For example, you can freeze Aether Quartz into Cold Quartz. You can throw Cold Quartz at enemies and they will get the slowness effect for 4 seconds. You can sharpen your Cold Quartz and get Sharp Cold Quartz which you can throw at enemies. Sharp Cold Quartz gives the slowness effect for 4 seconds and does a heart of damage.
Maybe an upgrade for the Continuum Orb? You can combine 4 Continuum Orbs to get a Block of Continuum. Place the block down and shift click it and you will get a random item. However, you have a higher chance of getting a good item from a Block of Continuum.