I've heard good things about raising kids bilingual, however since my wife has the same mother tongue as I we decided against it. I envy the people who have the option.
Also, there's no reason you can't start your child young with a second language. The French, in particular, are more than happy to train your child in French from a very young age pretty much no matter where you are in the world (search for Alliance Francaise). My wife and I have different native tongues, and we intend to have our child go to a school where the language of instruction is a third different language. We have friends who have raised their son speaking French, Spanish, English, and Turkish. He is now learning Mandarin and is the most articulate 8 year old you've ever met. It really is worth the effort.
I'll save you some time, though. Essentially, researchers showed babies tapes of a bilingual individual speaking English, then switching to speaking French. After a certain age, monolingual babies were unable to pick up on the switch, whereas bilingual babies were able to detect when the speaker switched languages. Oh, did I mention? The bilingual babies were Spanish/Catalan bilingual. In other words, they were able to pick up on someone switching from English to French, while neither was their native tongue, indicating that being bilingual preserves elements of the language recognition portion of your brain.