There's more to jetlag than simply shifting time zones but I would imagine being on +12 will help a little.
As for how to get there in business; Air NZ. They operate daily via Los Angeles and depending on time of year 4-7 times a week through Hong Kong. Their return fare to AKL usually allows you to go either way. They also allow stops in both places. In fact, depending on how long you've got if you're prepared to find your own way from Los Angeles to San Francisco they fly from SFO to AKL as well so you can fly LHR/HKG/AKL/SFO drive or train or buy another flight along the coast then LAX/LON. We did it a few years ago and found them extremely good.