Where do I start .... It was - by far - the best Airbnb experience I had.
Everything was perfect for our large group. The b&b is located off the busy streets but is 5min away from Chateau Frontenac. So you won't be bothered but you won't be far from the buzzing center.
The hosts - Francis and Véronique - are both from Quebec and will be able to recommend restaurants, sightseeing etc.
The huge house is perfect for large groups : several clean bathrooms, a 10 seat dining table, a living room with high quality sound system.
Cherry on the cake : the morning breakfast. It embodies Francis and Véronique care for their guests. We ate fresh pastries, fruits, yogurt while we discussed our day plan and asked for recommendations.
In the end, we all wished we booked more nights. But since we loved the place and the city, we know we will come back.