Courtyard by Marriott Downtown Toronto
That's a tough area, if you want walking distance. Carmen's is all I can think of too.
I do like Byzantium (used to live in that 'hood), but if you're not from the city, you should know that it's in boystown and if your client is an "old boy" of the more conservative type, he may be more comfortable at the steakhouse.
Right across the street, Carmen's is terrific. And not stuffy. So second Mandy Lin. That'd be my first choice by a long shot (or unless your client is a vegetarian)
Byzantium just up at Wellesley on Church might work for a client, it's a bit chi-chi-ish.
Fuzion is up one more block -- variable reviews here.