We climbed the bridge when we visited Australia in 2010, and it is a once-in-a-lifetime experience. A few things you should know, because tickets are issued for a specific time and specific date. Our experience with the climb tickets is that they can be exchanged IF space is available as per your schedule. If you just show up at Bridge Climb, you'll have to take what's available, if anything. Our best advice is to have detailed discussions with either Grand Circle or OAT to ascertain the itinerary of your trip in Sydney, so that you can book a climb when it doesn't conflict with your Grand Circle itionerary, and book it as FAR in advance as you can. Be sure to take into account the time it will take to get to the bridge from wherever you're going to be let off by Grand Circle.
Clearly, the best time to go is in the early evening, when the sun goes down, but these trips are booked FAR in advance, so if you haven't booked your specific date and time slot, you're just going to have to take what if anything is available. If you can't get the sunset climb, we would not advise booking a night climb, despite the fact that these climbs are also in demand. The concierge at your hotel can book the trip for you for a date, if space is available. You should allow 3 1/2 hours for the experience.
You are not allowed to take ANYTHING on your climb; they will issue jumpsuits which you will change into, leaving all your clothes, valuables, etc., in lockers which are locked and which a key will be attached to a cord which you will wear around your wrist. Thye most difficult and scary part of the climb comes at the beginning, when you have to climb four sets of offset ladders to get to the top of the bridge. Once on the bridge, it's just like walking up a gentle slope and is not difficult, nor scary. The guide of your climb will take all pictures, which you may purchase afterwards. We recommend doing so. We have a great picture of us kissing on top of the bridge, which was published along with an article we( rather my wife ), wrote for International Travel News. If we ever go back to sydnry, you can be sure we're doing this again. We were the only people on our trip who climbed the bridge, and many of the others were sorry they didn't.