Hoping for some advice for flights to New Zealand

Round trip tickets are usually cheaper than 2 one way tickets, but I would price them out regardless. You may find a better deal on different carriers. I would also look at a round trip ticket to Auckland as the return flight from Dunedin will go through Auckland. You can check air New Zealand for a one way ticket from Dunedin to Auckland the day before your return trip. Be sure to look at seatguru.com for seat selection for your specific flights. The flight over the Pacific is long so a good seat will be beneficial.

Edit: Make sure you look at arrival dates because you cross the International Date Line. We flew to Australia on a Thursday and didn't arrive until Saturday. The return flight arrives on the same day as departure.

RT flights are usually cheaper so you might get on airline websites to check prices, which become available 330 days prior to departure. We flew American Airlines round trip TUL to AKL in May, which was cheaper than Quantas. Not sure about Air New Zealand whether you get service at BWI or PHL. We used Air New Zealand to get around once at AKL, with tickets bought separately with Air New Zealand, apart from the AA flight. Cathay Pacific might also be an option and their flights are much more comfortable and with exceptional service. You also might check out other South Pacific carriers like Japan Airlines. February is one of the warmest months in NZ and June is one of the coldest so that might affect pricing also. Be sure to allow her time to visit Australia using NZ Airlines for quick flights to Sydney or even Hobart, Tasmania, one of our favorite places. You might find that if you get to LAX on one carrier, you could find a bargain flight to AKL with another carrier that services the South Pacific, but that might be too much of a hassle. Good luck.

Just checking Air NZ now, Feb 21 BWI to Auckland with a return from Dunedin on June 19 is $1562.

If you use something like skyscanner you'll see that routing via Sydney or Brisbane will give you a lot more options. The additional competition from having other airlines such as Virgin AU and Delta makes the flights generally cheaper. I've done this before and at the time the cost saving was significant enough to offset the inconvenience of the 3 hour additional flight in the wrong direction.

From November (I think?) Air NZ will be flying direct from Chicago to AKL, otherwise the options are West coast (SFO, LAX and Vancouver) and Houston.

If you do look at flights that are not direct from the USA to AKL, do check the total journey time. Anything with overly long connections or routing via Asia, I would rule out.

If you are looking at Air NZ, make sure you also check www.airnz.co.nz as opposed to the .com version when looking at domestic and trans-Tasman flights. Jetstar is the other domestic carrier (a bit more budget and considered a bit more unreliable).

The flights prices do fluctuate wildly, and there is normally at least one airline offering specials. Might be worth getting a fare type that will allow date changes on the return flight without extortionate fees.