Well, that Mazurek song was out of the blue, and it left me pretty sockless, especially when the horns come in around 4:00. It's a perfect blend of planning and improvising.

Here's another work that really surprised me: I was looking up some of Charles Albertine's arrangements, including his version of the theme from the film The Pumpkin Eater, but only found the original (by Georges Delerue), which is darned fine, and that got me started on a Delerue kick. https://youtu.be/bcfqdai4LIk

Also this one by Louis Moholo that turned up when I was researching some of the jazzier Canterbury groups, like Chris McGregor's Brotherhood of Breath:

https://youtu.be/CJlP7nX_qtY

Another perfect blend of the planned and the improvised. It even knocked the socks out of the sock drawer.