On our second floor, in two bedrooms we have window alcoves (see picture below). They are around 39 inches wide and around 70 inches long. The window sill is about 23 inches high. We are trying to figure out how to use that space -- we've talked about a window seat at the end, or an L-shaped seat that goes along one side and then ends in a window seat. Some storage for books would be nice, as neither bedroom has a bookshelf currently. It also might be nice to be able to put a twin bed in that space in a pinch. Any ideas or advice for us? Thanks!!