Well , Montreal is relatively a good city. I fly there for business purposes every year
Restaurants are decent in downtown , you could try on Sherbrooke Street , there's plenty a good places.
If you and your partner love asians restaurant... The Chinatown is a couple of streets away . Otherwise , just take the subway and head to Le Plateau , over there you will have plenty of things to do .
What can you do over there?
Well you can talk a walk at the old port , although it's pretty freakin' cold in the city ,especially at this moment of the year , but the view is still hella worth it . Thus, if you have energy you guys can enjoy skating on the ice rink that the city has installed for the winter .
You can also go shopping around, Montreal is known to have good designers in the city and downtown is probably the best place to start diggin' up .
As for night life, it's pretty dope . Just stay downtown and there's enough lounges and clubs to fit everyone's tastes. You can meet cool people , it seems like the city is very friendly to the tourists.
PS : If you're an open smoker...
Weed in Montreal is one of the best I have ever smoked,it's everywhere .