At the entrance of Badaling, there is a cable car station but not tobaggan. There are 2 toddlers with you, so I don't think great wall is a good choice, but you may try Badaling(https://www.travelchinaguide.com/china_great_wall/scene/beijing/badaling.htm) where provides cable car service. I think Beijing Happy Valley(https://www.travelchinaguide.com/attraction/beijing/happyvalley/) is also a good place for children.