Well amelia is definitely your best bet here since she's the local, but definitely the zoo!!! Their zoo is very good, and famous. I loved it when I was there at 10 years old.
You gotta go get dinner at Casa Bonita. Again, loved that place as a kid. Its a Mexican restaurant where the dining entertainment are cliff divers and navigating through caverns, and etc ...
Casa Bonita - the fun Mexican restaurant in Denver
And I don't know if its still there or not, but we were swimmers growing up and LOVED Celebrity Lanes. In addition to a full arcade and about 40 bowling lanes, it had at least one olympic size pool and countless water slides. It was a dream come true!!!
Enjoy your trip!