The Bay is gigantic and you can get some pretty sweet deals during their Bay Days.
I'm a big fan of the convenience of the location (connected to the Eaton Centre). It's directly above the Queen subway station and can be accessed via the PATH.
The store is currently going through some major renovations so it might be confusing navigating the place.
Tip for men: new men's section is on the 5th floor. My favourite is TopMan.