ok. i had to get out 'a history of the piano concerto' and remind myself of the ones that have unusual orchestrations. i guess manuel de falla was pretty cool. 'nights in the garden of spain' being for piano and orchestra. also, he composed a harpsichord concerto that wanda landowska played - and was scored for a chamber ensemble instead of full orchestra. to me, that shows sensitivity to the instrument (harpsichord) and the volume compatible. like both are weighed in the scales. although, here it says that falla viewed all six of the instruments as solo instruments but gave the harpsichord greater prominence.
also, joaquin rodrigo is one of my favorites - but i think he only wrote a guitar concerto 'conceirto de aranjuez' - but, i like the colors used in this piece.
ravel was another great orchestrator, imo. and poulenc. who, also wrote a harpsichord concerto 'the concert champetre' - and whom adored wanda landowska also. he wrote 'the pastoral concerto' also for a large orchestra. and 'aubade: concerto choreographique.'