I like the Idea of having at least two big continents. Maybe another 3, with medium islands (that can have one or 2 cities and zones to explore).
I say that because I like the idea of the vast sea, full of possibilities. Long shores to explore, with different kinds of creatures and ancient stuff. Beautiful view from cliffs, coastal fortresses, hidden caves at the coast or inner sea dungeons. Maybe in a place in the ocean a floating city/fortress (Waterworld reference). And to travel between continents you have to use a ship, so those harbors can be "alive", always having people traveling, when a new player with low level can frequently see people passing by them, including high level players (that could even stop to help or share some buff or knowledge).
I prefer this than a idea from just a continent, surrounded by water. That you don't really need to visit the harbors to travel, since you can just travel by continent.
I don't know, the idea of a vast sea without... well, without nothing... empty...