For Ives, try "Variations on America." Also the 2nd String Quartet. Fourth Symphony is magnificent, but takes some getting used to if you are not already familiar with the sound of Ives. The Second Symphony is also a favorite, particularly the ending.
Havergal Brian is also very interesting. I have the Gothic Symphony, and listen to it, but I prefer some of the others: 6th, 16th, 22nd. A Shropshire Lad is also very nice.
I am a fan of Brian's Third symphony (probably his most "normal" work) and his Fourth. I have not yet heard his others. I wish that the infernal BBC could locate "Prometheus Unbound."