What to hang on this wall?

I have probably talked about this a thousand times, but I have my reasons! This is the most important wall in the house and we still haven't decided what to hang on it.

Ramon suggested that maybe we should put a question mark like this one. I don't know if he was joking or serious.

I was thinking that probably a large mural would be the best choice, or maybe a wall decal. If the mural doesn't result then I would have to go with other options, like grouping framed art just as we did in the dining room. I really would like to have a mural wall behind the sofa, but they can get a little pricey.  Let see what happens.

If you have any ideas, please help us.