I somehow spent my life mostly unaware of the music of the Romantic era. Well, not so much unaware as deliberately ignoring. Stupid, I know, but that’s the reality (I can tell you why but that’s another thread.)
A while ago I stumbled onto Schubert’s Trio in E-flat major. And that led me to more, much more, of Schubert as well as (unsurprisingly) Schumann, Mendelssohn, Chopin, and of course Beethoven.
Piano pieces opp. 116-119 (especially 118/2 and 6, then 116/2, all of 117, 118/3 as well as 119/1)
Piano sonata n°3
Piano concerto n°1
Cello sonata n°1
Varitions on a theme by Paganini
That would be an essential starter kit.
And I know that you mentioned “non-symphonic” but his symphony n°4 is one of the towering achievements of the genre, an absolute must-have.
I don’t know about that. I would have thought that people with “less-trained ears” gravitate to symphonies and other orchestral music over solo piano and chamber music, because they like the lush orchestration or the varieties of tone color.
In addition to Brahms (as recommended by Les Espaces Du Sommeil), make sure you check out Dvorak. He wrote a lot of good chamber music (the “American” string quartet and the piano quintet are good starting places) as well as orchestral music (his “New World Symphony” may be his most popular and accessible work).
Liszt’s Sonata for Piano in B minor is one of my favorites. I actually wrote a form analysis paper on it for my music theory class back in the day.
Richard Strauss wrote a couple French horn concertos which are highly regarded (and fun to play).
Felix Mendelssohn’s Violin Concerto in E minor is a favorite.
Among other chamber music pieces, I love Romantic-era piano quintets:
Brahms’ in F minor
Dvorak’s in A Major
Schumann’s in E-flat Major
Borodin’s in C minor
Also wonderful are these piano trios:
Clara Schumann’s in G minor
Fanny Mendelssohn’s in D Major
(No, I’m not virtue signaling by mentioning these works composed by women. They are truly a delight. Fanny’s oozes with great melodies…listen for when the first movement’s main theme recurs in the last measures of the last movement).
Sonata in B minor an excellent choice. I believe the OP would also enjoy Liszt’s Piano Concerto #2. It’s an often overlooked piece that has always mesmerized me with its beauty and dynamic contrast of opposite emotions. It runs counter to many people’s misconception that Liszt only wrote bombastic, virtuoso music that no one can play but him (which he did, and I love all that, too).
I’d add to the list the Brahms Sextets and Piano Quintets, Mendelssohn’s and Schubert’s Octets, Schubert"s Arpeggione Sonata.
And perhaps you could push the envelope a bit to include Puccini’s Crisantemi, Rachmaninov’s Cello Sonata, and some Ravel -:the String Quartet, the Introduction and Allegro, and Le Tombeau de Couperin.
These names might be a late for the romatic period, but nobody’s mentioned Tchaikovsky or Debussy. About Rachmaninoff, there are several versions of a story about him coinciding in a hotel with his Prelude in C-sharp minor and Harpo Marx. The Wikiversion, for those who haven’t heard the story:
The information in the last sentence appears to come from Harpo’s autobiography. In other versions of the story, it’s claimed that Rachmaninoff hated the prelude and Harpo knew it.