One of my favorite topics. I lovoe the point about the subtle being as important as the flashy and the choices as well.

Here are a few of my favorite subtle solos:

Guitar: "I'm Set Free" by the Velvet Underground (I think the soloist is Lou Reed, not Doug Yule): https://youtu.be/wfzoyDOXfzY

Saxophone: "All the Way" by Caravan (tenor sax by Jimmy Hastings-starts about 4:26 and continues through the verse, plus a subtle flute solo as well--plays under, not over the chorus, starting around 6:00): https://youtu.be/umW1wH9SQFQ

Organ: "A Place of My Own" by Caravan https://youtu.be/Bt1inf8CRnE

Organ: "No Time to Live" by Brian Auger and the Trinity: https://youtu.be/SbRON01CSMY

Drums: "Hibou, Anemone, and Bear" by Soft Machine (drums by Robert Wyatt; solo starts around 4:35; the segue to the next song is missing). Headphones and a good quality version recommended.