This is a great thread, I think russian composer's (in general) are the ones who can better catch the idea of melody and fluidity in their music.
Rachmaninov: etudes-tableaux, piano concertos 1,2,3, his songs are marvellous (Oh, don't be sad, How Peacefull, and his 3 russian songs...), four pieces, preludes, musical fantasies, Musical moments, nocturnes, ...
Tchaikovsky: Piano concerto no1, the seasons, and mainly other orchestral works, widely known.
Scriabin: sonatas (nos.1, 5, 9...), études (op2, 8, 48), piano concerto Op20...
I'm starting to find Korskakov.
Prokofiev: piano concertos 2, 3, sonatas 2, 3, 6, 7, 9...
Well, I do love russian composers...
