While the average temps may be in the high 60s and lows in the mid 40s... Colorado can be temperamental. It's not out of the picture that there may be snow.
LoDo (lower downtown), RiNo (River North), Santa Fe Arts District, City Park, 16th Street Mall, The Highlands
Red Rocks Amphitheatre, Flagstaff Mountain, Boulder Flatirons (Chautauqua), Manitou Incline (it's harder than you think), feel free to ask Kelsey or Nick for great hikes too.
iFly Denver, The Wild Animal Sanctuary, Butterfly Pavillion, Denver Zoo, Denver Botanic Gardens