I've been researching this question myself as I am going out to Whistler at the end of the month. And I'll tell you that I'm not coming up with much good information. Apparently, there a few free overnight spots in Lot 4 but I have a feeling they go fast. According to the W/B website, "Creekside is blessed with 1,200 stalls of complimentary underground parking" but I can find no evidence that overnight parking is permitted. As far as I've been able to figure out this and the other free lots are for day skiers only. The W/B website has a link to other pay parking locationshttp://www.whistlerblackcomb.com/get...king/index.htm
but you have to give your life history to register before you can even see what the prices are. But I'll give you a hint - one of the other pay parking locations is the Westin!