This is a huge favourite of mine: Alexander Goldenweiser and Grigory Ginzburg play the Valse from Rachmaninov's Suite No.2 for two pianos. I love the laid-back tempo, the subtle rubati, the wealth of detail, the sultry tenor tone when the big tune comes through - and no histrionics or thumping. Just a perfectly-measured mix of musical haute couture with the poetry of partnership.
Goldenweiser, besides being a famous pedagogue and one of the central figures of the fabled 'Russian School' of pianism, was a great friend of Tolstoy's, played to him frequently and kept a notebook about his meetings with the great writer which was eventually published as Close to Tolstoy (if I can track down a copy of this by hook or crook, we'll come back to that later). More about Goldenweiser at the Toccata Classics site, here.