Now that I understand the question (merci pour les explications Celine et les autres), I can give you my opinion on good French gifts to bring (since I'm a bit of a collector of French souvenirs myself).
For the chocolate, I wish I understood what you're all talking about (but I guess I'll just have to wait till my next trip to France in 2 yrs or something and buy up some to try) but my opinion is that for the kids, as long as it's tasty, it doesn't have to be particularly expensive or a particular brand (we all know kids will eat any chocolate at all, no matter what) but I'd go for interesting - here we have the chocolate Freddo frogs where you can collect the frogs of different colours/flavours - if you have something of that equivalent in France, some kind of character on chocolate or bon bons, you could bring some of those and say they're the latest craze (even if they're not
) and the kids will take them to school for 'show and tell' and be rather impressed (assuming they're not already eaten by then!)
As for the jigsaw, c'est drole, sauf pour it rather reminds me of my jigsaw of the Eiffel Tower I bought years ago....not 10,000 pieces, but so much clear blue sky that by the time I finished the it, I decided to glue it and frame it and it's been hanging in the bathroom ever since (actually I know quite a few people who've framed all kinds of jigsaws).
For the rest of the stuff - I rather agree with Flo - keyrings are a great choice - if you're French, you'd almost be expected to bring SOMEthing of the Eiffel Tower - one of my first penfriends 15 years ago sent me a little model of it (not a plastic one, but proper metal).
She also sent me 2 quaint tiny plastic dolls wearing French costume, a boy and a girl, also things I'd never seen before, so therefore rather interesting even if you don't like dolls, as I don't.
Other suggestions for the hosts - I think soaps are a great idea (unless such a world known brand that we'd be able to find them here in boutiques) and easier than perfumes as I think choosing perfume is a difficult thing for somebody you've never met.
Par exemple, when Ozman was here, amongst other great things he brought me this savon avec un cigale embedded in it - absolument fantastique & I've never seen such a thing before.
Oh, and another thing I forgot: a lot of Australians collect Fridge Magnets! (Indeed at my parents place you can barely see the fridge underneath them any more! The craze used to be stickers, but now it's more keyrings and fridge magnets). Souvenir pens are another one.
Hope this helps and that these things haven't already been listed, as I couldn't manage to read all of the forum.
Kate