Before I started home schooling my 10-year-old daughter last year, she attended the one child-oriented foreign language program our neighborhood has to offer: a once-a-week Mandarin program at the local art center. It's a largely art and play-based program, and, after about three years of it, she'd learned perhaps a couple of dozen words and phrases and a few characters (many of which she'd forget each summer).
When I started homeschooling her, I figured we'd intensify the Chinese instruction one way or another. My Mandarin is quite rusty, but I'd had an intensive year in grad school (following an intensive year with Cantonese in Hong Kong), and I thought learning it with my daughter would be a great opportunity to polish things up and make some new headway, especially with the written language.
A few months later I found myself abandoning this and switching over to French. As a linguist, I do love the idea of exposing myself and others to non-Indoeuropean languages. But the more time we spent on Chinese, the more aware I became of various practical challenges that aren't such an issue with French.
One has to do with available resources (and, of course, my familiarity with what's out there). I've had a long history with French and have long known about French in Action, which is the best available, child-accessible, audio-visual language curriculum I'm aware of for any language. In particular, try as I might, I haven't been able to find anything comparable for young English speakers learning Mandarin. There are a number of software programs out there that purport to teach all sorts of languages (most notoriously, Rosetta Stone), but these, imho, are so highly deficient they they aren't worth bothering with--even if they didn't cost hundreds of dollars.
Then there's the issue of retention. In comparison with French and other Indoeuropean languages, Chinese presents two disadvantages. One is its writing system. Mastering the thousands of Chinese characters required for basic literacy demands hours of daily practice. I've seen first hand how a short hiatus can result in massive forgetting. One simply cannot learn to read anything of substance in Chinese without a long-term commitement to significant daily practice. Another is its vocabulary. Chinese words are especially challenging for English speakers to remember because they bear no resemblance to English words.
So here's how I ended up viewing my options. If my goal is for my daughter to learn a language spoken by billions that may someday become a job-opportunity-expanding lingua franca, or a language whose pronunciation, vocabulary, and written form (though not so much its morpho-syntax) differs greatly from English, and I can commit both her and myself to the hours, days, and years of instruction (or if I don't care about her learning the written form of the language), Chinese is just the ticket. But if my goal is fast mastery and easy retention of a spoken and written language, my daughter is better off with one that uses an alphabet and whose words bear some resemblance to English words.
Which brings me back the original lingua franca. Like other Indoeuropean languages, French shares not only our basic writing system, but also tons of cognates (glace-glacier; sympathique-sympathetic; regarder-regard; to name just a few my daughter has recently observed). This means that English-speaking French learners are immersed in mnemonic devises. The effect of these cognates goes in the other direction as well: learning a Romance language like French enhances one's acquisition of many of the more sophisticated elements of English vocabulary. Cognates aside, French difers from English along the more linguistically interesting dimension of morpho-syntax, arguably at least as much as Chinese does. It therefore presents a nice combination of (1) mutual reinforcement with English vocabulary and an easily-mastered writing system, and (2) morpho-syntactic challenge and a window into some of the morpho-syntactic variability of the world's languages.
Other Romance languages--Spanish, Italian, and, of course, Latin--offer a similar combo. But today's world offers few opportunities for aural/oral practice, and zero real-life conversational opportunities, in Latin. And, much as I'd love to relearn Spanish or learn Italian, I haven't come across anything like a Spanish in Action or Italian in Action. Meanwhile, I'm seeing the tremendous efficacy of Pierre Capretz and his French in Acttion play out daily in the huge progress my daughter has made since last February, which I estimate to be already well over the equivalent of a year of 7th grade French.