Movement 5 (Finale) of the Visions suite. GPO + Strad. After a bit of a tense opening, this turns into a lullaby with an unlikely duet for violin and tuba in its highest register. I'm still working on movement 3, but should be able to post it in a few days, along with new mixes on the complete suite.
Visions V - Dust Ascending (Larghetto): mp3 file - pdf file
It's not in the official description of this piece, but from the 2-minute mark to the end, there is a sunset.