Most NZ motorhome fleets list a 4-berth or 6-berth layout, but the numbers hide a real difference: in some 4-berths the second bed is the dinette converted nightly; in others, both beds are permanent. With kids that distinction matters more than horsepower or kitchen size. A permanent bunk above the cab (Luton bunk) means you don't reset the lounge every night. A drop-down bed in a 6-berth means the parents lose the lounge after 8pm. Decide which trade-off you can live with before comparing prices.
Berth choice with kids
A family of four with kids under 12 usually fits a 4-berth comfortably; teenagers stretch a 4-berth and a 6-berth becomes worth the extra rental cost. Two adults plus one small child can use a 2+1 berth if you don't mind the dinette conversion. Holiday parks all accommodate 6-berth lengths — the limiting factor is the campsite booking, not the vehicle width.
School holidays and pricing
NZ school holidays (early April, early-mid July, late September-early October, mid-December to late January) push motorhome rates up sharply and fill holiday parks weeks ahead. Australian school holidays overlap two of those windows. If you have flexibility, late February through March or late October through mid-December gives you school-holiday weather without the school-holiday prices.
What to ask the depot before pickup
Confirm the booster/child seats by age category, not just "child seat needed". Confirm there's a Luton bed if you booked one — a handful of layouts called "4-berth" sleep four only by converting the dinette. Confirm the holiday-park membership card if the rental includes one (Top 10 or Kiwi Holiday Parks discounts add up across a 2-week trip).