Since you’re interested in traveling, I would say french. It is spoken in a very wide variety of countries all over the world, you have a lot of resources to learn it and it’s related to the other languages to know. Other languages might have more speakers, but if youre just interested in the visiting a lot of wholly different places, it is probably the best one.

I have to agree on the DaVinci Code, it’s impossible to get pass the first chapter.