Which spark plugs should I use for a stock G35? Also what should they be gapped at?

I run NGK iridiums. They come pre-gapped.

Anyone know what the stock gap is on the stock platinum plugs?

+1 NGK iridiums.

If you buy OEM NGK plugs (platninum, iriduim, copper), they'll be gapped to the correct spec. I believe the spec is 0.044" or 0.045". It should be listed in the owners manual.

BTW, I'd run nothing other than NGKs in a VQ motor.