At the time of year you're coming, hotel rooms are fairly easy to come by, so be flexible with your plans. Revelstoke, Kicking Horse and Lake Louise are all very big mountains, though I would say the first two will take more time to explore because there's a lot of in bounds terrain that isn't visible from the lifts and requires hiking to get to.
In mid to late March, the best skiing at Revelstoke will be on the upper mountain, and it will be very good. The base will be at it's deepest, there are fewer crowds and big storms are still coming through. You'll still be able to ski out to the base area (barring a catastrophic warming in the valley) and this year has a been a good one for snow on the lower mountain, so skiing 5,000-vertical-foot fall-line groomers will be in the cards (Snow Rodeo and Pitch Black, when they're groomed top to bottom are the best runs in the world). If you want to mix it up, go cat skiing with K3 for a day, or hire a guide to take you to Rogers Pass.
Kicking Horse has awesome terrain, but not as much snow as Revelstoke. It's best for skiing steep alpine chutes, whereas Revelstoke has better tree skiing and fall-line groomers. The same storms that hit Revelstoke hit Kicking Horse, but by that point they've lost a lot of steam. I would avoid it on a weekend, because there;s basically only one lift and the lineup can be crazy if it's busy – though the time you're going shouldn't be too bad.
Lake Louise, IMO, has the best terrain of the three — the back bowls are amazing — but by far the worst snow. It is higher and colder, so coverage will be good on the whole mountain but the odds of skiing freshies is slim.
Anyways, I would drive straight to Revelstoke for at least two days. If the snow is good, stick around. If it isn't, get back in the car and go to KH or Panorama or LL or Sunshine.