Naxos seems to have recently acquired the distribution rights to some of Delos Records catalog. Delos put out a number of recordings of symphonies and whatnot by American composers, usually performed by the Seattle Symphony conducted by Gerard Schwarz. So for a small amount of money you can get a large amount of music - which works great if you're just sampling.
David Diamond's symphonies (any of them) are worth hearing. As well as his Violin Concerto and Kaddish for Cello and Orchestra (kind of defeating the "voice getting too dominant" concept). Post-Romantic modern music, generally written in the 1940's - 60's, and not harsh on sensitive ears. A few of these works are available on Naxos.
Alan Hovhaness is greatly represented on a variety of labels. Although American, he incorporated many different elements reflecting his Armenian heritage and Asian studies into his music. A lot of his works are based on mountains and other natural entities and have a kind of beauty-of-nature feel to them. His symphonies (all 60 or so), concertos, Prelude and Quadruple Fugue, and And God Created Great Whales for orchestra and humpback whales are my favorite examples of his work. Quoting composer Bernard Rogers, "Hovhaness comes from a small planet where it is always Christmas and where there are no bad sounds."