You could also check out the Denso TT series plugs. They have iridium on both the center and ground electrode, and should really last a long log time. Those could be 500 hour plugs if you treated them well, although I would still just plan to replace them in 1/2 that because they're not very expensive.
They have an IK16TT/IK20TT for short reach, and IKH16TT/IKH20TT for long reach.
One thing to be absolutely aware of is, spark plugs are a MAJOR item in the counterfeit industry. Absolutely buy them from a reputable place and that doesn't include amazon. I have a friend who took the time to order some from a few places and if you check out online resources for how to spot fakes, he compared them and found that some were definite fakes.
I checked with sparkplugs.com and they guarantee no counterfeits on these, as they pick them up directly from Denso.
Do some reading about counterfeit plugs and you'll see what I mean. Can't trust anything these days.