Accommodation
Montreal has a huge amount of accommodation that spans from luxurious grand hotels, through fairly anonymous Downtown business hotels to boutique bed and breakfasts, numerous hostels, and hundreds of homestay listings just both in and around the centre and in the suburbs.
Location
Not staying right in the centre is of lesser importance in Montreal, since the metro connects many parts of the city quickly and with little fuss. If you arrive with a car staying outside Downtown will certainly make parking easier. But if you do stay outside the centre, try and make it close to a metro station.
Prices & Booking
Prices tend to be reasonable by North American standards and availability generally good, though you might struggle last-minute on the weekend of the Canadian Grand Prix.
Most hotel search engines have good coverage in Montreal, so try any favorite you have first. Otherwise, the Momondo hotel search engine is good for drawing its results from multiple sites.
The leading homestay site in Montreal is Airbnb, which has good coverage at every price level.