I Am by Boysen is underplayed.

Deir in De has some slow pretty stuff.

Plenty of transcribed hymns/sacred songs such as Blessed are They, Jesu, Joy of Man's Desiring, and a Pie Jesu.

I also love As Summer Was Just Beginning by Daehn, Nimrod from Enigma, and Down Longford Way by Grainger.

Those are all in the first *five* pages on the PML if you search by "100 - Band, Grade 3."

I'm sure you can find a few dozen options if you expand beyond that. The Grade 3 list is quite good.