What are the ages of you children? Generally, there are tons of activities provided by the resort - keep in mind that there are two Marriott resorts in Park City: MountainSide and Summit Watch. This link: http://www.vacationclub.com/resorts/sm/default.jsp and http://www.vacationclub.com/resorts/ms/default.jsp should give you a few things to look at concerning activities. You might also try going to www.parkcityinfo.com, www.parkcitymountain.com and www.deervalley.com for more detailed info pertaining to the individual resorts and area information.
There is mountain biking, hiking, rafting, fly fishing, alpine sliding, zipline rides, just to name a few. If you want, feel free to contact me directly, as I worked for both of the resorts at one time and currently work for Marriott Vacation Club in Salt Lake City. I live in Park City. My email address: dax.massengill@vacationclub.com
Dax
Dax M.