Wineguy.
I go to Montreal every quarter for business. Usually Day trips but do stay over the odd night. You won't have any problem with the language. As Smurph says everyone is very accomodating with English. Maybe a few die hards in some local spots but you will get by.
I see you are going with a lady friend so I will pass on the adult version of Montreal that 1837 and Doc S. know and love, as it has some of the best establishments in North America. But we will leave that to another time.
If Dollars are free and easy I would suggest to stay in Old Montreal. It is beautiful and very historic. Nothing like walking around with a lady friend and letting the romance set in.
There are plenty of Hotels this one is my favorite
http://www.hotellestjames.com/
It is amazing and very historic. As well the spa there is out of this world. The spa is in the old bankers hall of Montreal. alot of history.
I have stayed at many hotels in Montreal and this one is my fav, but if you want to use your Marroitt points then stay at the M and then go to the St. James for the spa.
As for eats, two restaurants that you have to go to, both at different ends of the spectrum.
http://www.restaurantgalianos.com/
A very nice restaurant. Try the lamb chop. Have not had it better anywhere.
The other place you have to go for lunch is Schwartz's deli.
http://www.schwartzsdeli.com/
Across town, but the best montreal smoke meat sandwich you will get anywhere. Buy the spice to bring home with you and use it on your favorite roast.
My other favorite place to stay is the Ritz Carlton. I would not stay there unless the company is paying as it is overrated, but what you should do is go to the Ritz bar and have a cocktail, great place.
The other place to go is the casino. Fun place and why not bet on your holiday while you can!!
1837 will be able to fill in more, but that is my run down. Any other questions let me know.
Have a great time!