One of the things that the packaging of the Deutsche Grammophon Complete Edition box of the music of Johannes Brahms has revealed to me is just how little music Brahms composed for orchestra. There are only five CDs in the Orchestral Works section, which comes down to the two early serenades, the four symphonies, and two concert overtures. Then there is the orchestral version of the Opus 56a Haydn variations (which, in spite of alphabetic ordering, has always struck me as a post hoc reflection of the Opus 56b two-piano version) and the WoO 1 Hungarian dances (which were probably preceded by the four-hand piano version). There are then three CDs to cover the two piano concertos, the violin concerto, and the "double" (violin and cello) concerto, bringing the count up to eight. Finally, there are three CDs of Works for Chorus and Orchestra, one for the German Requiem and two for shorter works, the most familiar probably being the Opus 53 rhapsody for contralto, male chorus, and orchestra. In other words there is an orchestral presence on only eleven of the 46 CDs in the Deutsche Grammophon box.
This "census" reminded me of what I basically already knew, which is that Brahms' two "strong suits" were the keyboard and the voice. There are nine CDs in the Piano and Organ Works section, only one of which is for organ, while another two are allocated primarily for the four-hand and two-piano works; but the piano plays a major role in the canon of chamber music, which fills eleven CDs. Similarly, the piano accompaniments for many (most?) of the song settings (another eleven CDs, covering both the Lieder and Vocal Ensembles collections) stand in their own right as impressive keyboard writing. That leaves only the four Choral Works CDs, most of which are a capella or relatively modestly accompanied (the outstanding exception being the Opus 17 songs for female chorus, two horns, and harp).
From the point of view of a struggling amateur, I also have discovered that, while there are certainly works that make heavy virtuoso demands, once you figure out how to get your hands around them, the notes tend to be pretty much "keyboard friendly." I have had similar experiences with Robert Schumann (who, for all we know, brought out that side of Brahms) and Joseph Haydn (whose influence is easily detected). This contrasts sharply with my efforts to wrestle down Ludwig van Beethoven (even if the struggle is eventually rewarding) and my ongoing frustrations with Frédéric Chopin, whom, for the most part, I prefer to leave to others. Franz Schubert occupies a middle ground between Beethoven and Brahms; but then I have always enjoyed the anecdote about a Schubertiad at which he could not play the fugue from his own "Wanderer" fantasy! Franz Liszt is another matter. I had a teacher in Santa Barbara who encouraged me to go after Liszt in order to get beyond the usual pedagogical conventions, rather in the spirit behind Simon Rattle's efforts to get the orchestra of San Francisco Conservatory students to get beyond their conventions when performing Richard Wagner. On the other hand Liszt's arrangement of Beethoven's first symphony is, in many ways, far more "keyboard friendly" than many of Beethoven's own piano compositions. After Brahms, of course, the rules of the game start to go through all sorts of changes; so any discussion of "keyboard friendly" music in the twentieth century should be held off for another post!