Frankly, most of my favorite Québec spots aren't loaded with ski-in/ski-out options.
Sutton has a bit of something for everyone:
http://www.firsttracksonline.com/sutton2004.htm
Although the "glades" are wide-open compared to the Eastern standard (La Fantasie is one notable exception), this place is a blast. It's spread out upon a long, broad ridge. Need it slightly steeper? Move to skier's right. Need to wind things down a bit? Move to skier's left. The eastern end is like one big roller coaster, where you're free to wander anywhere you wish and drop stair steps back to the base of the lift.
There are a limited number of condos and chalets slopeside along the gentle trails at the resort's western end.
Also in the Townships, Orford's groomers are a bit monotonous, but the trees...OMG the trees!
http://www.firsttracksonline.com/orford.htm
Here you'll find some limited ski-in/ski-out as well, at the base of Mont-Giroux, but it's very limited.
Alas, as you'll see in other threads on these boards - particularly from last year - Le Massif ain't what it used to be:
http://www.firsttracksonline.com/lemassif2002.htm
Massif du Sud is one tough little bugger in places, but there are no slopeside pillows:
http://www.firsttracksonline.com/massifdusud.htm
Mont-Edouard is tough, too, but with only 1 slopeside option:
http://www.firsttracksonline.com/montedouard2002.htm
Le Valinouet is the natural snow capital of eastern Canada, but you might as well be Sir Edmund Hilary trying to get there:
http://www.firsttracksonline.com/valinouet2002.htm
Personally, for my taste, I'd bypass Tremblant and Mont-Sainte-Anne, the two most well-known Quebec options. However, you say that the group is primarily beginner and intermediate, and they certainly have the most diverse options for those abilities as well as the most alternative resort options for those who don't plan to pound the slopes from opening to close. I tend to aim toward areas with a high quotient of naturally challenging terrain, and my thoughts above reflect that. I prefer to ski hard and sleep hard, and resort amenities therefore mean much less to me. As all of these others are somewhat smaller, you'd pretty much have to plan to link at least a few together into one trip to make the voyage from Manitoba worthwhile. For example, you could combine Sutton, Orford, and even Jay Peak in Vermont, or combine Mont-Edouard and Le Valinouet. You could travel to Quebec City and ski Massif du Sud, Le Massif, Mont-Sainte-Anne, Stoneham and Le Relais. It's sometimes tough for a westerner who's used to wide-open spaces to visualize just how close things are to each other back east.
Have you thought about dipping south of the border instead? Jay Peak, Smuggs, Stowe, and Sugarbush are all more diverse options than any of those listed above, and with the current exchange rate the loonie isn't so bad down here right now.
The biggest problem here, however, is the last week of March. That's crapshoot season in the northeast thanks to low elevation, as Tony Crocker has drilled into our heads so many times by now. You could have pow, you could have rain, you could have freezing rain. Anything is possible. You'd pretty much have to check the weather a few days before to decide whether or not to go for it. Feb. 1 - March 15 is the dependable season in the Northeast.
You'll find links to all of our Quebec resort features here:
http://www.FirstTracksOnline.com/qcski.htm
and our Vermont resort features here:
http://www.FirstTracksOnline.com/vtski.htm
