What should I build i'm minecraft? I need ideas?

A while ago a friend and I started a world on minecraft that we just kept adding to. We now have a high rise, a indoor pool, a complex whit several buildings, and a greenhouse. I need new ideas of things to build in this world to make it even bigger and cooler than it allready is. Anything helps, Thanks!

A hospital, a park, a dock with boats, a high cliff that leads to water below with a cottage on top, a maze, a castle, a dungeon, a treehouse, a mob farm, a casino, a sky scrapper, a bridge, a school, a hotel, replicas of your favorite character, etc… Lol

Try to make a
-hotel
-resort
-automatic wheat farm (any automatic farm)
-fort
-pirate ships
- throwns
-massive treehouses
-houses inside mountains
-hidden houses acquired by redstone
-redstone houses
-roller coasters
-trolley lines
-some sort of boat war thing
-park
-amusement park
-water park
-water slides

Hoped this really helped, I mean as always the options are endless. You just need a creative mind and be a decent builder

One thing i did was i dug down to the bedrock, tnt blasted the mess out of everything to make an enormous open area, made a hold under a large, isolated oak tree that led down to it that fell into a pool of water, and made a bunch of structures and called it "wonderland". For example, making an extremely lagre house like that of a giant, with large scultptured furniture and the sort, or a dinosaur skeleton made out of cotton with a sign saying "don't forget to feed the jabberwacky -Hatter".

another thing i did was block-jump-stack my way to space and built a spaceship, then made a stream of water that led down to the ear like a tractor beam.

final idea was i made a lage city in the sky, and called the area that was blackened by the citie's shadow "the bad lands" and the city itself "heaven". Just ideas for things a little more creative than theme parks and hotels and such