Spanish is increasingly common, yes.
However, that doesn't mean your children shouldn't learn any other languages.
http://www.fll.vt.edu/French/whyfrench.html
I let my children pick. I started learning French as a child since a lot of my family speaks it. I used to be fluent, but not so much anymore.

I chose French to expose my children to because I basically knew it and one of my major family goals is to tour Europe in several years and French would be enormously more helpful than Spanish.
I also took a German course which the kids became interested in. The kids watched Dora and dh used to speak Spanish, but we really haven't had more Spanish exposure than French any of the places we have lived. They seem disinterested in learning it even though I've offered and I'm not one to push it. I want to learn Spanish, though. I have tried before but just don't think I can.

We are also learning Greek and Latin right now together. My oldest (9 yo) is self-teaching herself Greek and I hope to get Rosetta Stone someday. She is studying mythology and it's amazing how much a basic knowledge of Greek and Latin root words and letters has helped her with all her other subjects *and* in picking up words of other languages. Sometimes we'll watch a movie with French or German, etc. subtitles and she can pick words out better than I can!
We find tons of French kids books on Amazon and Amazon Canada. It's worth the shipping for a much wider selection.