Instead of doubling back on your route from Christchurch to Queenstown, head east from Queenstown toward the coast and take the coastal road through Waimate, Timaru and Ashburton on your way back to Christchurch.
Stop where you will. What make interesting trips are the little discoveries you make along the way.
If you arrive back in Christchurch early enough, check out what you missed in Christchurch on the first day and make up for it.
Then say Goodbye to the South Island. For now.
