Here's a few additional pics of the space to give you a better feel for it as a whole!

Hi, mshutterbug. I like your concept. It's essentially a "rotating" gallery wall and I think it will be interesting and fun. I'd go with shelves in a similar finish as that of the built-in top. In consideration of the shorties in the family, I'd add a light weight but sturdy step stool. (It's a drag sometimes, but working for what we want tends to build character!) It'll also serve as nice perch for a smaller person. Since you're thinking about ditching the framed cork board, consider some art in its place. As I'm sure you're aware, art is something that enriches and educates young and old alike. I think a lamp would be good, too. A table top terrarium would be educational and likely enjoyed by everyone in the family. You can make it and care for it together. They're really fun! I added an abacus, because it could be a learning opportunity for everyone in the house. They also have an orderly, sculptural quality I find appealing. Your aesthetic may differ. Here's a mock-up to illustrate my ideas. I hope it helps! (The rug placement/size can be addressed when and if you choose.)

Are you in an area where snow might be tracked in? If so, consider luxury vinyl plank flooring stead of laminate. Laminate will warp and buckle if drips aren’t wiped up quickly.

We just bought a townhouse that has a very similar style staircase. About half of the people with this model painted the living room beams and the staircase white. I don't like that look at all and much prefer to see the natural wood. I too think it gives a much more contemporary vibe than painted white.