If you're going downtown Byward Market, there are two places that I would recommend. Real Sports (owned by MLSE) and The Senate.
Keep in mind you'll likely need to reserve a spot now if you want to even think of watching the game at Real Sports. I haven't been able to get in there yet even trying to reserve for a Saturday two days in advance....
I really enjoy the Senate as well, but can fill up pretty quickly.
So many places. My choice would probably be 3 brasseurs (3 Brewers), Georgetown Pub, Mill Street Brewpub or The ClockTower. I choose these for the awesome choices of beer. On the quebec side, you can go to Pele-Mele, Chelsea Pub, Le Forum or Cage aux sports.