There's a bewildering choice of London hotels. It all depends on your priorities/travel arrangements/budget. Obviously, you know more or less what you are going to get with the big chains like Best Western or Holiday Inn. You also need to balance cost against location. There's a decent website here that allows you to search according to date and proximity to central London, along with a rough guide as to standard.
http://www.laterooms.com/en/k16295585_london-hotels.aspx
Obviously, if you see one you fancy then you can double check its ratings and reviews elsewhere. You can search in Canadian Dollars too.