Planning Your Time
If you are making just one trip to New Zealand, you're probably starting from Auckland and working your way south; in doing so, you should also consider making some "dog-leg" detours across the North Island.
For example, between Cambridge and the Waitomo Caves head east to catch the geothermal action of Rotorua. Or, from the Waitomo Caves, before turning west to Taranaki head south an hour or so to Whakapapa, the northern gateway to Tongariro National Park. From the south, turn inland from Wanganui to reach the park before heading to Palmerston North.
For a backcountry adventure go south from surfing spot Raglan, keeping close to the coast, then inland to the Waitomo Caves before heading back to the coast to follow the Marakopa Road to Taranaki.