Park City does have an alpine slide (they have a "slide" version and a "coaster" version) as well as a zip line. Snowbird also has an alpine slide along with a few other things as well. If you're looking for a hike, Timpanogos Cave is a good one considering the ages of your kids. Lagoon could be fun if you're wanting to go to an amusement park for a day. They have a new roller coaster that just opened up that's supposed to be pretty good. A couple other options depending on your family's interests would be Hogle Zoo or the Living Planet Aquarium.