A School Bus Tour of New Zealand

While in Fiji I met a lot of people who are on there way back to the U.K. They all had advice for what to see and do in New Zealand. I've been told by a number of people the best way to get around is to buy a fairly comprehensive bus pass for one of the hop on hop off services in operation. I thought I knew which company to go with, but found out they didn't go to Napier, an Art Deco town I'm really looking forward to seeing. A few people also recommend seeing the East Cape, which isn't traditionally on the tourist route, but is worth a visit.
So after much indecision, even a walk in the rain to Albert Park, I have finally bitten the bullet and bought a ticket for the Kiwi Experience.
This was the one company I thought I could definitely rule out as it has a reputation as a bit of a young party tour. I'm sure I'll be the oldest person on the bus (that's including the driver), but hopefully it won't be too bad. Although who am I kidding? The tour I've booked is called the "Funky Chicken". Is it too late to cancel?
My first day is Auckland to Mercury Bay on the Coromandel Peninsular. From what I understand, the bus stops at interesting sites along the route and even calls into a supermarket before dropping patrons at their chosen hostels. Each day you can ask your driver to book accommodation for that night, and with it still being the low season this should be quite easy.
I like the fact I won't have to cart my rucksack from hostel to bus depot, instead I will be delivered door to door. However this could be at the cost of having to perform the Macarana....