any of the waltzes from Op. 34
particularly no. 2 or 3
or
one of the Op. 62 nocturnes, which are not too hard if you can play "grade 8", but they are difficult to interpret. Many lesser pianists have failed to understand these nocturnes unfortunately, and I know many people that don't like them simply because they've heard inadequate recordings!
When they're intepreted "properly" though, so-to-say, they are wonderful. :)