I miss.....
Cheap gas. Seriously, you think you have it bad?! Try $2.20 per liter! That's over $8.00 per gallon. Yup. Americans are spoiled even with the "high" gas prices.
Knowing where to find things in the grocery store.
Instinctively walking past a person the the correct side (Kiwis drive on the other side of the road, and they walk on the other side as well). I find myself swimming against the tide in malls, on stairs in the grocery aisles.
Central heating. I've learned to layer even inside and wear slippers (Richard's because mine are still on a ship somewhere in the middle of the Pacific Ocean).
Being the one without an accent. Sometimes I hesitate to speak (yeah, big surprise, I know) because I don't want to have to answer the same old questions about where I'm from, why I'm here etc. Also, even though they speak English in New Zealand, the terminology is different.
Understanding the health system. As messed up as it is, the US health system is easier to navigate than the system here where public and private health cover different situations and different doctors.