Tahoe is going to be hit this year. They've been pounded with snow. If it quit snowing right now (and it isn't going too) there would be plenty of snow for spring style riding in April-May
The main reasons I am heavily recommending California is the weather. It can snow then and snow a lot, but if it's not snowing it's generally sunny and warm. Other places like Canada (Colorado-Utah too) are more susceptible to getting a blustery windy day at that time that just freezes and crusts everything over. Fine if you live in those spots, you can pick and choose your days. For a vacation, I think you want reliable. California has the best spring skiing in North America. A few can come close to rivaling it, but none exceed.
Banff is a great area, absolutely stunning. So I doubt you would disappointed there. Riding conditions can be a lot more variable though. At the time of year you are going, I would not count on getting fresh snow. It's just not that likely. If you do, it'll probably be good the day it is snowing and for a few hours after it quits. That is about it. That time of year is just too warm for powder snow to hold up for more than a day.