For another orchestral solo, there's a beautiful soaring solo in the second movement of Shostakovich's "Age of Gold" Suite. I believe in the score it's written baritone horn, though many of the recordings I've heard sound like it's performed on a euphonium.
Here's a recording of the Chicago Symphony under Stokowski: https://www.youtube.com/watch?v=11yL9osbC_k (starts at about the 5:20 mark)
Willson 2900 TA-1 Euphonium - Denis Wick 4AM
Yamaha YSL-643 Trombone - Bob Reeves BrassArk 5G "Gladstone"
Yamaha YSL-8440 Trombone - Denis Wick 5BS
VMI 3301S BBb Tuba - Schilke Helleberg
Past:
York Preference 3067 Euphonium - Denis Wick 4AL
Benge 165F Trombone - Benge Marcellus
Wessex BR140 Baritone - Denis Wick 6BS
F.E. Olds Special Trombone (ca. 1941)