Some features we do need more of, that aren't too hard to fit in-

-Inland seas! Think of the Aral, Dead and Caspian seas.
-Lakes! Lakes everywhere! The Great Lakes, Lake Baikal, Lake Victoria, Lake Chad, Lake Malawi... Big lakes are awesome, guys!
-Rivers! Rivers can be used as highways, provided they don't have rapids or waterfalls serving as a chokepoint, and are a lifeline for cities.
-Volcanic islands, archipelagos, and atolls! The west Pacific is riddled with islands! Think of Polynesia, Micronesia, Indonesia, the Philippines, the Caribbean, Japan, what have you!
-Reefs! Where did the Drenched Flowerbed go? It was our resident Great Barrier Reef analogue.
-Mudflats? Sure, why not?
-Salt pans! Possibly as a result of a failed attempt at making a sea? That said, though, there's not much civilisation-wise you can do with a salt flat other than trade the salt.
-Trenches... Actually, we don't need trenches, the whole south-center of the Fractal Sea practically is one. Plenty of space to be deep, dark and spooky. THAT SAID they do tend to pop up around islands and undoubtedly contain Blood Wells...
-Cenotes! Vakarlon made a cave system that riddles Galbar and the Submaterium presumably connects to it, so having some giant flooded holes in the ground would be awesome.