Window seat with built-in bookshelves. Could use IKEA: Hemnes daybed kitchen pullouts each), and Billy bookcases each or with uppers each). Total cost with knobs, trim, paint, etc. would be about The skylight is a nice touch too!
this is another idea I saw in that client's house. Useful for stuff besides babies, of course. They don't want to stay all day in those little baskets anyway. Sweet idea for baby organization in a closet. You could even use it as a changing station.