Atlantis is a deathtrap.
All the Pretty Little Horses is not a great song, even if the arrangement is ok, and it's one of the hardest Grade 1s to make sound good on the list.
Chorale Prelude is very, very difficult - lots of meter changes, odd beat entrances, and the like.
Sea Song Trilogy doesn't fit your needs, as you state that you don't have strong trumpets or flutes, and it needs both. Plus, why play three songs when you can play one? (even though they're short..)
That leaves Madrigal for Band, which is rarely performed, or Kingstree Overture (which averages a composite score of 1.91 on Brynnpark, so that's way closer to a 2 than you might want) - or the pieces arranged by McGinty, which will have the same issue with what instruments play melody.