What is considered the correct usage of mix versus mixture?
As an example, is either of these two sentences considered to be more correct grammatically than the other?
1) The trip was a mix of hiking and climbing
2) The trip was a mixture of hiking and climbing
To my ear either is acceptable, but I presume one is better than the other?
The differences between mix and mixture are subtle.
A mix of something is often descriptive of the make-up or components of a mixture:
The castle was built from a mix of sand and water.
A mixture, on the other hand, is the thing that is mixed:
The cake mixture is often a mix of eggs, flour, and oil.
There is a lot of wiggle room in usage and the distinction of when to use one or another is fuzzy. A general rule of thumb is to use mix when naming the individual parts, and mixture to describe the whole.
In the examples you gave, I think both would be acceptable, because you are either talking about a mix of hiking and camping that make up the trip, or the trip’s “mixture” of hiking and camping.