If you are looking for some holiday fun you can take the whole family to look at Christmas lights and it's free! In Denver the City County building is lit up beautifully, along with the iconic Clock Tower.
In Littleton you can enjoy the lights on Main st, shop for gifts at locally owned stores, and enjoy a nice dinner at any of the Main st restaurants.
If you have some extra cash to spend take your family to the Botanical Gardens. Their light display is gorgeous, and they offer free hot chocolate!