like the cat that got the cream BrE informal
like the cat that ate the canary AmE

Stott looked like the cat that got the cream.

He just kept sighing, and ate without noticing what was on his plate, while Hester looked like the cat that got the cream.

Mr President, the large groups in this House must be feeling like the cat that got the cream, for there will now be millions pouring into their party coffers, and they will be able to afford fun and games throughout Europe.

He had this look he'd get sometimes, like the cat that ate the canary.

She was grinning like the cat that ate the canary.

"Stop sitting there looking like the cat that ate the canary and tell us all.

Back at the table, Leslie was still acting like the cat that ate the canary.

"You look like the cat that ate the canary," Anna said.

Len, in fact, looked like the cat that ate the canary (as Bobby's mother often said).

"We have a few planes here, Hawk," the general said, his smite looking like the cat that ate the canary.

"Raise you right back again," Block said, dropped a dollar in the pot, and smiled like the cat that ate the canary.

I waved her off again and took the dragon out of my purse, where it lay snuggled in a handkerchief, looking for the world like the cat that ate the canary.

Once more Waffing brought his beer mug to his lips, this time clearly for dramatic emphasis, for when he laid it down, he was grinning like the cat that ate the canary.