I also like MacDowell, there's a lot of great music of his that isn't played a lot. His four big Piano Sonatas are underrated IMO. There are other suites like the "Woodland Sketches" that have some very attractive short pieces in them, the "New England Idylls" for instance; several great pieces in there, including "From Puritan Days", "To an Old White Pine" and "Of Salamanders". The "Sea Pieces" op.55 are also very good. You should investigate this literature more if you already like "Wild Rose". Gottschalk is extraordinary, the first composer to use material from America and the New World, although the forms the materials are in is standard 19th century virtuoso format. A remarkable composer...
I also enjoy the piano music of Gershwin, Beiderbecke, Ives, Griffes, Barber and some Copland. And the ragtime composers.
I've only heard a few of his pieces but the music of Arthur Foote seems to be worth further investigation...