The Rockies have lots of snow and slopes for sledding and tubing in the winter. For fun family tubing near Denver, visit Hidden Valley in Rocky Mountain National Park. Hidden Valley used to be a family downhill ski area and has now been re-developed by the Park into a wonderful sledding area that is easily accessed by car.
A picnic pavilion provides shelter with 14 picnic tables, and flush toilets are available year-round. There's also a winter warming room (both handy things to have with kids in snowsuits!).
Tube rentals are available at Estes Park Mountain Shop on the Hwy 34 entrance to Estes Park, and at The Warming House on Hwy 66 on the way to Beaver Meadows entrance.
When the kids get cold and tired, head into Estes Park for a hot chocolate and a bite to eat at one of the many restaurants in town.
A soak in the outdoor hot tub or private indoor spa at your weekend lodging will feel great! Here's a list of lodging properties in Estes Park with hot tubs.