Ottoman empire, that is.
I used to think “ottoman” was a funny word. Heck, who am I kidding—I still think “ottoman” is a funny word. But as an adult I’ve come to recognize their utility. Especially when I can store things in them. Or tell a child, “You need to sit on the ottoman so that we old people with bad backs can sit on the actual couches and chairs.”
Anyway, they’ve got a two ottoman set at Amazon for $35.99 shipped, which is kind of a steal just on shipping savings alone. Hide the smaller one in the larger one, or use the larger one for storage (and look, the top flips over to be a tray, which is snazzy). Either way, it’s an efficient, inexpensive way to expand both seating and storage.
These would be particularly good in a kids’ playroom, because it gives extra seating and storage and you won’t have to sweat it if they end up destroyed. (Side note: At what age of the children, exactly, do I get to stop appending “… if they end up destroyed” to every household consideration?)