When we went to the Petronas Twin Towers, we wanted to go up in the Skybridge. They only allow a limited number of people to go a day, so they give out tickets with specific viewing times; our time was 4:45 pm, so we had to come back later. So after playing around in KLCC Park and lunch in the mall, we walked 25 minutes to the KL Tower, and took the high-speed lift up to the observation deck. It gave a beautiful, panaramic view of the city, including birds-eye view of the Petronas Towers.
You can read more about the KL Tower here.