There are tons of papers available that would go with your midcentury home. Many people tire of a paper quicker than they are ready to redecorate and they can also look dated in a couple of years. Metallic papers were big im midcentury...perhaps a metallic silver paper? Are you also considering paint? You can get it in so many textures and a blue wall to match the blue in your loveseat would be lovely with some midcentury art and sculpture, or photographs on it. A mirrored wall with or without art or sculpture would also work with midcentury. These treatments are easier to adapt should you wish to change the look slightly from time to time. I would suggest replacing your stairrail with chrome or acrylic if that is in the budget...see how well the loveseat frame looks with the fabric? I hope you will post the "after" photos for us to see. Above all, enjoy the process!

There are many examples on houzz of contrasting counters for perimeter and island. For example butcher block on island and stone on perimeter or a solid color on one and something with movement on another. I would only mix two stones if one had movement and one was fairly solid. The stainless on perimeter and something else on island sounds good to me. Here is a pic of stainless counters with what looks like a stone breakfast bar. (I hope I understood your question right). http://houzz.com/photos/3137660

Now for Mr 16 months... I really can't decide. His room is going to be on the cold side of the house, with not so much sun so I want it to get that cozy sort of feeling when you come into it. I was thinking yellow or orange curtains? But then I don't know what colour to do the walls. These are some fabrics I like:

Beauty and practicality; Mmmmmm ..... When it is something that you love .... real wooden floors. Now vinyl just gets dirty , Ply looses it functionality, real wood however gains a patina. You want that. People pay thousands of dollars for that. Go with the most genuine example that you can afford of what you love. Factor in your budget and add to it, an area at a time and be pleased that your life gives character to it every day. By analogy; A mahogany french polished table will just give you a nervous break down every time someone doesn't use a coaster ... a hardwood table can be replenished over and over with hard wearing protective surface .... which you can repair. If you love it, if it adds genuine warmth and character, you won't mind maintenance. You won't be saying ...." look at this floor , isn't it amazing? It looks just like the real thing?"