Some random foodie recommendations:
- Jean-Paul Hévin, the chocolatier, now has a mini-boutique at the entrance of Galeries-Lafayette Gourmet
- Bellota-Bellota also has a stand in Galeries Lafayette Gourmet, although their restaurant in the 7th (18 Rue Jean Nicot) is also worth a visit for some of the best tapas, and Bellota ham, in Paris
- If you don't make it to Ladurée while in Paris, there are now two outlets at CDG, one past security at terminal 2F, and a portable cart before security at terminal 2E.
- If you're jet-lagged and eating at odd hours you could try a late lunch at Yves Camdeborde's restaurant at Odéon, Le Comptoir du Relais. They serve food late into the afternoon, and don't accept reservations for lunch. If you show up at 2:30pm you will avoid the queues.
- Another restaurant worth trying is Frenchie (in the 2nd) which is not far from Galerie Vivienne (I was assuming you were referring to this passage when mention the Passages...). Although it's probably too late for a reservation here - you'd have to rely on a last-minute cancellation.