Bistro fare for non-snooty parents in Paris?
I've got the parents coming to town next week and I want to take them out for some good grub. Although my mother is a big fan of fine dining, my father is much more into informal and rustic fare. I'm already planning to take them to Chez Denise and Les Trois Marmites, but I was wondering what other places in Paris might offer a similar experience. Le Cave de l'Os à la Moelle is a possibility, but I can't make a reservation ahead of time and it's on the other side of Paris for us. Any suggestions?
Also, one related question: my parents are both big seafood eaters and I want to show them proper bouillabaisse, as I think they'll find it's very similar to Peruvian chupe (i.e., they'll love it). I've had good bouillabaisse at La Brasserie du Dôme, but the service has been execrable, so I'm not eager to take them there. Where else in Paris would you go for proper bouillabaisse?
thanks in advance!