Am too lazy to read other posts; my idea's might have been mentioned already
Amusement Park-like theme:
Basicly just a map that uses ''happy colors'' that make you enjoy looking at the map. I mean you can add a Roller Coaster Track with the train at the station so players can walk on the tracks for chests. A Ferrywheel (spelling might be incorrect but I'm lazy atm to recheck) that can be the near the middle, Carrousel (possibly multiple) somewhere on the map, Bumper Carts, a Haunted House-attraction. Even possibly a Wild Water-attraction! (You get what I mean, just a map that looks ''happy'' with lots of attractions.
Savannah Map:
I might sounds like I feel like I'm sooo good but;
https://www.cubecraft.net/threads/minecraft-build-african-savannah.181317/ I honestly believe (as the Build team 99% of the time does a way better job) if you take this idea and details, make the animals look good and remove a lot of the grass it can make a real good SG Map. You can even make a cave system inside of the huge rocks. Maybe even a little camp with tents somewhere on the map. You get my idea, just a nice looking Savannah Map.
Pirate Map:
I know there used to be an old SG Map called Pirates and I'd love to see a revamp of it. Just a huuuuuuuuuge island with caves, sunny beaches, hidden treasures and big pirate ships surrounding it. Can't realy describe much else of it, it's just an island with pirate ships.