Broader overview of music samples can be heard HERE
I would base my composition on melodic themes using different instrumentations that evoke a gentle uplifting feel that is positive yet honest.
There would be a journey of sorts, starting with a gentle lead in introducing the melodic material simply (perhaps on piano) with subtle string “washy” sounds. The subtle washy string sounds will grow and give a sense that a journey is about to begin.
Then as we move further into the track the initial melodic material introduced by the piano is developed further into a slightly richer context using orchestral strings.
An example of this can be heard in the sample track of “Constellations” supplied on above. One hears the melody for the first time simply on the piano at 16 seconds and then it repeats but with richer embellishments of strings at 40 seconds.
The journey continues at a lyrical easy pace with different sections as heard in the other excerpt supplied called “Gold Fever”. The first section introduces a wistful uplifting melody that is reinforced with different instruments. Then at 54 seconds a new section of music is introduced. This will give the variety sought in the brief so that people on hold don't feel like they are hearing the same thing over and over again.
We return to the original melody which is heard at 1min 35 but with more embellishments so the tune is memorable but not repetitive.
I would focus on writing music with a strong string orchestral elements with some woodwind and piano colouring.
I hope this gives you a direction on my initial thoughts on how I would approach the music.