About an hour north of Boulder and one of the best things about living in Colorado. Hikes of all levels, camping and Trail Ridge Road, a very scenic drive along the highest paved road in the state (although its average winter closure date is 10/23 so check conditions). Try Twin Sisters or Gem Lake if you don't have a NP pass or don't want to pay admission. Reservations for entry end 10/11 so you don't need to worry about that.
Downtown Boulder has a lively walking mall with street performers, restaurants, and shops. Also Tim works here, or did when we went to work. Make sure to visit the Boulder Bookstore and Into the Wind kite/toy shop. Boulder creek is two blocks away if you want a nice creekside walk after.