I am responsible for organizing a group dinner in Paris for approximately 20 (Canadians) on the last night of a week long wine tour through Alsace and Champagne. Ours will be a fairly food savvy group and this will be our only evening in Paris so a typical bistro with classic french fare via a set menu would be preferred. We will be based near the Place de la Republique though anything in the broader vicinity would work. Chez Michel will be closed (we are looking at a Saturday evening in May) and Aux Lyonnais won't accept a large group reservation unless one books the entire restaurant (though I think this was an excuse to avoid the embarrassment of having to accomodate a large group of english speaking diners - le gasp!). Astier and Ambassade d'Auvergne are both possibilities and I'd appreciate the insights of anyone able to compare the two for such an occasion, or offer other suggestions?