All the places I've stayed have been very similar in quality. It depends on how much $$$ you are willing to part with. One way to save is to get a place that is not a walk-to-the lifts type. The bus system is very frequent and free. It takes you to the bottom of both mountains and to the village; room for skis and gear is built in. This may not work well for a family of 6, though.
If I was taking little ones on a ski vacation I wouldn't take them to Whistler. Too big. A smaller area would give me a greater sense of ease knowing they wouldn't have as great of a chance of getting lost. I could relax a bit more. To counter that last opinion, I did have a wonderful experience with the ski school on Blackcomb when my kids were small.
Check here: http://www.whistler-insider.com/
to get a better grip before you brave the corporate sites.