Upper West Side vegetarian lunchtime?
Telepan has an excellent prix-fixe lunch menu ($28 for 3 courses) and there are vegetarian options for each course (and if you call ahead to them they can prepare something based on your specific request). The decor is great.
Jean Georges also has a prix fixe lunch that you can add additional entree for $12. Needless to say, both food and service are excellent. They are very accommodating about vegetarian requests. These two places should be "upscale" enough to show your sincerity.
For more casual you can go to Landmarc which also has great food, though I find the place a bit too crowded and busy for your need.