Clothing/Shoes/Weather Gear: When we were in Whistler in July it was generally in the high 60's (F) and the one day it got into the mid 70's all the Canadians were going around talking about how hot it was. They were wearing shorts and tank tops when it was clearly leather jacket weather. My point is, bring something warm to wear even if you are visiting in the summer.
Luggage and bags:
If you're staying in a hotel and have car standard suitcases. If you are at a hostel or lodge type thing and well you are a backpacker...then bring your backpack.
Clothing/Shoes/Weather Gear: Ski Gear: Snowboard (or skis),Helmet (they're cool now), water proof ski pants, ski jacket, ski goggles, water proof gloves (mitten style is annoying if you are boarding).
Underneath Gear: Warm but thin, lycra pants, polypropylene shirt and fleece vests are good. You will stay nice and warm even if you get wet!
Toiletries and Medical Supplies: Painkillers if you're a beginner.
Photo Equipment: Disposable camera if you don't want yours smashed.
Miscellaneous: Small pack to carry miscellaneous stuff in like a snack or lunch.
It depends upon the time of year - during winter, obviously, winter clothing is necessary. I was there in May and wasn't skiing, so I didn't need heavy jackets. It did rain alot, so a raincoat was needed. Hiking shoes helped with all the walking that I did.
Miscellaneous: In Vancouver, I had heard that there weren't many grocery stores in Whistler or that they were pretty expensive...so I brought food with me from Vancouver...canned goods, bread, etc.... Which was a good thing because I was staying at the HI hostel and the nearest place to get food was a bus ride or long walk into town.