When you're building a house, there's always inside walls and outside walls. The outside walls are where the windows go; they give a nice view and let in that bright sunlight. There's not much more that can fit on these walls other than windows.
The inside walls are where the magic happens. After you've finished hanging up a few family photos, find some thought-provoking abstract art to hang. If you can't find any original paintings, don't go out and buy prints or copies of artwork; you're walls deserve better than that. Pick out some Artreka abstract art and you'll be sure to add some character to those happy walls of yours.