I went to New Zealand in 2016, it is beyond amazing!!!! My husband works for a travel company, so we went with a tour group. Are you opposed to going with a tour, because that would take all the worry out of everything, no driving, no scheduling, you just meet up and all the details are taken care of. If you need to choose between both islands, do the SOUTH island, it is truly breathtaking. But the North Island is very pretty too. We come from the East coast, on our trip over, we flew to LAX and stayed over one night. Same with the return trip home. Highly recommend breaking up the flights this way. We upgraded to the very back of the plane, there are two seaters (look on Seatguru), soooo much better than sitting next to strangers for 13 hours. You will love NZ!