My fault for being ambiguous about the word "bigger", thanks for pointing this out. It's true that you're not looking for a large area per se. What you want is a large perimeter. The best starting click would be a whole lot of thin tentacles stretching out across the board, not a giant square-ish clump.

That is, you're trying to maximize information. A large rectangular area doesn't give you nearly as much information about the board as a tentacle-y one, because most of the squares don't tell you anything but their own value.