Australia/New Zealand/Fiji was our first GCT trip in 2001. It was an outstanding adventure! We attended a concert at the Opera House and had gotten the tickets on-line before leaving the USA. Tickets were available at the venue as well. We did the Bridge Climb, at the last minute, and have never regretted that decision! Our PD helped us rearrange our schedule so that we could do the climb and even made arrangements for us to dine at a later time at the restaurant since our meal was an included dinner.
If your PD contacts you before your trip, you may want to tell him/her about your concert plans and ask for their opinion. We wanted to attend a concert in Dublin and our PD told us what the exact schedule for that particular day would be before we ordered our tickets. We also were willing to forego an included dinner so that we could attend "My Fair Lady", sung in Estonian, in Tallin...a great evening! We have found that our PD's have been willing to go above and beyond to help us experience "real life" in the country that we are visiting, especially if you have a particular interest in something like music, art, etc.
I just gave my wife the Pandora charm of the Sydney Opera House for Christmas for her travel bracelet so the memories linger.