I have a client I was recently working with...she has a similar setup. She is buying a small eclectic collection of art, and framing it in different thickness's of black frames. Similar to the first pic I am attaching.

She chose this piece and framed it in a frame that has a little big of thickness,
http://fineartamerica.com/saleannouncement.html?id=f4777aaf3c57ebeb2028d6c8fbf27733

You can throw in a family photo, and add different things you love. Go black and white or mostly BW with splashes of color. Making the collage can be a very fun process.

Here are a few pieces that would great as part of a collage like that.
http://angelina-vick.artistwebsites.com/featured/the-dill-3-version-2-angelina-vick.html

http://angelina-vick.artistwebsites.com/featured/the-garden-of-your-mind-bw-angelina-vick.html

http://angelina-vick.artistwebsites.com/featured/make-music-angelina-vick.html

http://angelina-vick.artistwebsites.com/featured/read-free-your-mind-angelina-vick.html