The question I get asked most often before a trip is which lens to bring. My honest answer is usually just one: a 35mm.
It is wide enough to shoot a street scene or a cramped market stall without backing into traffic, but tight enough that a portrait still looks natural rather than distorted. If I can only carry one lens on a ten-hour flight, that is the one that comes with me.
A second lens earns its weight only if it does something the 35mm cannot: a fast 85mm for portraits with real background separation, or a compact zoom if the trip is mostly landscapes and architecture, where a wider field of view actually matters.
Everything else – the extra bodies, the filters, the tripod – stays home unless the trip is built specifically around needing it.