The Fairmont is ski-in/ski-out, so this is the perfect activity. We plan to ski Tuesday - Friday before the wedding, and you can also ski Saturday morning and/or Sunday afternoon. Whistler is on the epic pass (we're know, we're sorry, Ikon friends) and you can buy them here - https://www.epicpass.com/pass-results/passes.aspx However, epic sells passes by the day ahead of the season at reasonable prices. Right now, in July, they're $113 CAD ($81 USD) for 1 day and that decreases as you increase the number of days. If you plan to ski, please BUY YOUR PASSES NOW, prices start rising in September and will likely be close to $200 USD for a single day in January.
The Scandinave spa in Whistler is a well-known spa with thermal therapy (sauna, hot and cold baths, etc.) that also offers massages. Recommend booking early.
For little ones, or those who don't ski, Whistler also has a tubing park.
Lost Lake Park and the Callaghan Valley offer a network of snowshoe-specific trails for you to explore (an entrance fee is required for these venues). All trails are clearly signed and maintained, with detailed maps available so you can choose your own adventure. Snowshoe rentals are available at the day lodges, along with food, drinks and other activities. Whistler also has a network of hiking trails which are perfect for snowshoeing in the winter, although they are not maintained and signage may be minimal. Recommendations include the Sea to Sky Trail, Cheakamus Trails and the new Train Wreck Trail. Pop by the Whistler Visitor Centre for maps and current conditions.
The Nordic venue of the Vancouver 2010 Olympic Winter Games, Whistler Olympic Park offers snow activities for all ages and abilities. Explore the park on cross-country skis or try biathlon. Rentals, lessons, adult and kids ski camps are available, plus dog-friendly ski and snowshoe trails. The park has a full service day lodge with cafe, retail and rental shop and ski school.
If you're not skiing and still want some gorgeous mountain views, you can take the Sea to Sky Gondola. Once at the top, many other adventures await. You will have access to a wide array of outdoor experiences, including two different interpretive loop walking trails with cantilevered viewing platforms, the spectacular Sky Pilot Suspension Bridge, numerous hiking trails, rock climbing, access trails to backcountry routes and much more.