If weight isn't too much of an issue and you're interested in branching out, maybe the 24-135mm?
It's a far stretch though, I'd admit
https://www.cinema5d.com/sony-28-135...ine-zoom-lens/
Reason I mention it is because focal length-wise, looks like you're making due with the current set, and if you need wider, you can always take an extra photo or two
The 135 gives a bit more stretch, and it also has video filming aspects in its design
Diverse enough?