These balconies are architectural features designed to give a feeling of spaciousness. In the entry it will make you & your guests feel like your home is nicer /larger / more spacious than it already is. I'd put a round sunburst mirror up there to catch people's eyes and let it go at that. There is not usually enough room to do anything in these places. Do you even need a reading area? or will it just be one more place that isn't used that contains dusty books that no one reads? OR not used If your area is larger, send the dimensions or a photo and hopefully we'll come up with suggestions.

Would love to see a photo to get a better feel of what you have described.
Cheers! Monique

I have the same issue in my house. Not sure if I should leave the space empty or decorate with a chair, plant. We actually do not use the space as it is connected to my son's nursery, but I keep thinking that there should be something decorative there. Open to ideas! Here's a pic.

It's usually best to draw the eye upward as much as possible. How about a stencil over the window? Here Or here or a faux wall paper stencil on the wall with the window only. There are many other wallpaper stencil designs too. Or try a chair or two and a table and a plant (as you suggested) maybe on a smaller scale? Here are other wallpaper stencils http://www.houzz.com/wallpaper-stencils