I love Ives. Two works of his I can recommend are "General William Booth Enters Into Heaven" (voice and piano) and Two Contemplations (orchestra).
Ives' father, George Ives, gave his son some words of wisdom that represent, in my opinion, a truly wonderful philosophy of music. Referring to the off-key singing of the town blacksmith, the elder Ives advised: "Look into his face and hear the music of the ages. Don't pay too much attention to the sounds--for if you do, you may miss the music. You won't get a wild, heroic ride to heaven on pretty little sounds." For listeners trying to connect with Ives' music for the first time, this may be a great place to start.
Ezra