wide grin
broad grin

His smile became a broad grin as he saw all the money.

Then he flashed a broad grin and took off running.

Every face in the room was split with a broad grin.

His broad grin invited her to answer it, and she did.

This last was said with a broad and friendly grin.

For him, it was the equivalent of a broad grin.

The boy who finally came up with it sat down, a broad grin on his face.

"Jack, I think you will want to see this," the chief of staff told him, with a broad grin.

He read through it quickly, his smile turning into a broad grin.

Her strong dark face was split with a broad grin.