Yeah I'm not crazy about the ending either. My (poor) excuse is that if it were included as a middle movement of a symphony, it wouldn't be the end of the piece, so I could worry about a more satisfying ending in the finale. I made a couple of attempts to write a coda, but couldn't come up with anything I was happy with, so I left it as is.
It's a bit of a stretch, I'll admit, and I'm certainly not at Beethoven's level by any means. It's not so much that I went directly from the A theme to the waltz, but that I went from A theme, to B theme, to waltz theme. I'll try to demonstrate:
I took the three-note ascending motive from the second violins in m.5 to build the B theme:
Instead of having the two three-note groups offset by one scale degree, I moved the second group up one scale degree, and tied the repeating notes together. Here's the first Violin in m.143, pg.12:
I continue to use these three-note units to build this entire section. Here's the first violin, m.151, pg.12:
I used the below motive from the second violins in m.3 to build the violin melody in .m.155, in retrograde inversion (and shifting the scale degrees around a bit)
Now to get to the waltz theme, I took the violin melody in m.143 and offset it by a beat, so the second note landed on the downbeat. This gave me the "shape" of the melody, which I altered the notes to be chromatically ascending instead of by scale degree, m.280-282, pg.21:
Like I said, maybe a bit of a stretch, but it helped me avoid coming up with completely new material at each new section, and resulted in melodies that I was happy with. To make the connection a little more concrete, I tried to hide a few of the motives from the ABA section within the C section:
Trombones/tuba m.400-403 is the B theme from the violins at m.151:
Violins, m.408:
Violas, m.305:
The chromatically ascending horn at m.139 is used for the flute, clarinet, and violin at m.346:
It's ABCABC, A (m.269-313), B (m.313-345), C (m.345-359), A(m.359-379), B (m.379-396) C (m.396-422). I tried to alternate the "moods" between each time the A and B themes were heard. A is first timid, then confident, B is first confident, then timid. C is first light and floaty, then heavy and bombastic (and I needed an excuse to use the trombone gliss lol).
Thank you very much for your thorough listen and insightful comments, as always! If the pandemic ever ends and I encounter you IRL, drinks are on me 🙂. I'm not 100% sure, but I think a symphony might be my next big project, but it will of course take quite some time...