If I were headed over to Montreal for another trip, I would definitely consider staying at Sonder Maisonneuve again! It is in the same block as the Guy-Concordia metro station, has one of the city's bike rental stations only a block away, lots of shops and restaurants close by, and the best matcha shop at the end of the street (very important)!
Note: upon reserving you need download the Sonder app to complete your booking. With that you will receive your check-in information. Might be confusing but I didn't find it all too bad. I kept my communication with Sonder through Airbnb since that's where claims would've been made if something came up.
Check-in: with the code they give you, it gives you access to your floor, unit, and amenities. Concierge was helpful.
Check-out: they have a floor where you can keep your bags locked up in case you're departing way after the check-out time. Super handy!
Amenities: loved the wet sauna/hammam! Sadly the dry sauna wasn't working. Pool closed a couple days when the weather turned. Gym and patio were opened. Awesome views at the top!
Unit itself: Was a bit disappointed that we didn't get the room that was shown in the listing, especially because we spent some time bouncing back and forth between two Sonder listings that had different pricing, different views, and layout. They explained that it was due to the bookings program that shifted our room to another room so that they could minimize the number of days the rooms are vacant. After speaking with the concierge and messaging Sonder about this, they made a suitable price adjustment. The units were beautifully furnished. If you want to use the Roku though, you need your own Netflix/Prime/Disney/etc account. Bedrooms were a bit of a squeeze but we weren't spending lots of time in the bedrooms anyway. If you're visiting during summer months, Maisonneuve location has AC.