Things To Do In Denver Area In December

My son and I are going to be in Denver December 12th & 13th and need some ideas on fun stuff to do. We will be going to the Thursday night Bronco game on the 12th and probably stay in Denver till the 14th. We like restaurants like you would see on Diners Drive Ins & Dives...nothing too fancy but good food. My son is 15 so everything is boring to him haha. Any ideas fellow BPers? I am sure i can Google for ideas, but would love some opinions form the locals.