I reckon Kalinnikov is the great undiscovered jewel in the crown of Russian music. Try the First Symphony or my own favourite, "The Cedar and The Palm". And one for what seems to be a majority of US correspondents here - why isn't George Whitefield Chadwick better known? The "Symphonic Sketches" in particular are marvellous, especially "Noel".
I agree with you on "The Cedar and the Palm". There is a wealth of tone poems that are rarely heard in concert. Another that comes to mind is Cesar Franck's "Le Chasseur Maudit". Also the late set of tone poems by Dvorak.
Chadwick's music is not heard that often even here in the US.
Agree about the late Dvorak pieces, especially "Othello" - even if it does go to sleep in the middle! If you haven't yet, try Lyapunov's "Zelazowa Wola" or Balakirev's "In Bohemia" among a host of worthwhile music by either.