George Gershwin wrote one of his last concert hall pieces in 1931, his Second Rhapsody. It was written for piano and orchestra on a commission from Serge Koussivitsky and the Boston Symphony Orchestra (who premiered it, with Gershwin, in early 1932). The piano isn't as central as it is in Rhapsody in Blue and Concerto in F, but is still a prominent solo instrument throughout the piece.
Contrary to what was written about the piece when it was first premiered, it was not written for the movie Delicious (pronounced "De-lish-ee-ous"), but was written prior to the film. Gershwin gave his two-piano score to the Fox Studios composer/arranger, who edited the piece down and used themes in the film. (Here the Wikipedia article is blatantly inaccurate.)
Unlike most of his other works up to this time, Gershwin orchestrated this piece on his own, after writing a 2-piano score. The score wasn't published until the early 1950s in a heavily revised version by Robert McBride. Michael Tilson Thomas made a fairly faithful reconstruction of the original orchestration in 1985, and that is likely what is used today when (if?) the piece is performed.
It's not as well-known as his other concert hall works - there are about 5 times as many recordings of Rhapsody in Blue as there are of Second Rhapsody - but I find it just as exciting to listen to. You can hear how Gershwin is advancing as a composer, continuing to combine aspects of the European and American musical traditions in ways vastly different than contemporaries such as Copland. (He described his sostenuto theme as "Brahmsian" and you can hear elements of the blues in it, too, in the use of the flat 3rd.)
There aren't any YouTube clips of the orchestral version, and the only 2 piano version I could find was of poor recording quality. Below is the piece, in two parts, played by the energetic Labeque sisters. (Just to clarify, it's one continuous piece but is broken up here.)
(Second Rhapsody, Part I: Allegro, etc. - Katia & Marielle Labeque)
(Second Rhapsody, Part II: Sostenuto e con moto, etc. - Katia & Marielle Labeque)