Type vegetarian into the Search This Board box at the top of the page for lots of discussion on the topic, some of it quite recent.
Somewhat more upscale than the reccos you've got so far is Au Cinquième Péché, whose menu always includes a totally vegetarian main, usually a variation on their delicious sweet potato gnocchi (currently with zucchini, roasted red bell pepper, feta and pine nuts). Vegetarian-friendly soups and elegant composed salads are available for starters, cheese plates and trippy desserts (chicory cheescake with speculoos topping and honey-caramelized endives, for example) to round out the meal. If you go the table d'hôte route, the vegetarian meal runs $30.
Not much "real" vegetarian in town, especially if your friend do not even eat fish.
a few that comes to mind :
Aux Vivres (vegan on St-Laurent); hippie-ish, but fun none the less.
Chuch/Chuchai (asian-ish on St-Denis)
La Faim du Monde (never been there, On St-Denis)
I'm certain you can get vegetarian friendly Indian in town, and probably get italian fare that suits you friends.