Since when is Mississauga an "hour's commute"???? Holy shit, I guess if you're riding a bicycle or your car doesn't do more than 50 kph.....
Anyhow, IMO staying outside the core will save you (a little) on the hotel rate, but you will spend more on travel to the core. If you stay in the core, you'll pay a little more for your room, but your transportation costs will be minimal.
It all depends on how you want to travel and how far.
Questions:
1) How familiar are you with the city? Are you comfortable enough to take the subway? This will open up all kinds of hotels around the perimeter of the core but you don't have to travel to Mississauga to get a cheaper room.
2) Tavel to and from the airport: There are shuttle buses that many downtowm hotels offer to their guests at no, or minimal charge.
3) If you're into things like the museum, AGO, theatre, centre island, harbourfront etc. and plan on hitting them while you're here, stay in the core and walk to them. You'll save on transportation costs in the long run.
I'd suggest the Roehampton Best Western at Mt Pleasant and Eglinton. It is close to great shopping areas (yonge n or eglinton and Mt Pleasant south of eglinton). it is a short subway ride downtown to the core and has nice clean rooms.
I think it all depends on what your budget is and what your interests are. For eg: if this "meeting" doesn't work out?