We arrive in Montreal via train on a Sunday morning in early October around 11:30. Our flight from Montreal is Monday at 8 AM. We tentatively have a hotel booked at the airport, as it seemed easier for the early morning departure. Instead of taking a taxi to our hotel directly to drop off luggage, we will try and find someplace to leave our luggage and hit the town straight away. We want to, of course, visit the Old Town, and stroll the streets, etc. We are looking for good restaurant recommendations and must see's.
I would recommend just dropping your luggage at the hotel concierge and not having to worry about it for the rest of the day.
You'll have about 12 hours in Montreal to do stuff, so I would stick to 1-2 areas. Since you're hitting Old Town, I'd recommend Notre Dame Basilica and lunch at Olive et Gourmando. Just north of there along the 2 Line (Orange) is the Mile End neighborhood. If you can get a reservation (or willing to eat a late dinner), go to L'Express. Schwartz's Deli and a couple of iconic bagel joints are also in that area if you want a classic old school deli (as close to NYC outside NYC). There a a number of great little bistros and Neapolitan pizza cafes in that area. Yes, all my recommendations are food lol.
On your way back to your hotel/airport, hit the Gibeau Orange Julep which is an old school Orange Julius.