I've learnt through experience that I should also bring along some sort of sensor cleaning device, like the LensPen SensorKlear.
In temperate countries, when the air is dry, things tend to get statically charged rather easily, and that includes cameras, making them a real dust magnet. It's frustrating when every shot you take, you can spot elephants on the ground, or UFOs in the sky of all your images.
May not be that crucial if you only brought one lens, though...