[kiwi_jono]

Welcome from NZ.
As to what lens beyond that, I say you need to spent some time taking shots to figure out what focal lens and capabilities of lenses you desire. Certainly you have good coverage from 16 - 85, but maybe some day a longer and / or shorter focal length calls your name. Or perhaps a fast 70 - 85 portrait lens. Or perhaps a macro. Or maybe that Limited lens with imaging pixie dust. Or....
Certainly different lenses can give you different capabilities but be warned they call it LBA (lens buying addiction) and most of us seem to suffer from it. I certainly have more lenses than I need (mostly older manual lenses that I still enjoy playing with) and keep threatening to sell some but rarely do.