Night Fury by Chambers is a fun action piece.
Armory by Standridge as well.
The Oncoming Storm by Rogers is a recent addition, but sounds cool and is playable. If you're up for C Minor.
Fortis by Gazlay is a little tougher than these and has a lyrical middle section that can have tuning issues. But it was a work horse for my borderline grade 1, grade 2 bands.
I've never played Serengeti Dreams, but a few of my friends have in 1A/2A and it worked out great for them.
Conviction by Larry Clark is a solid choice.
Korean Folk Rhapsody by Curnow is really pretty. That tune almost cost me a 1st Division, but they pulled it off.
Wildwind Overture by Kinyon is a more traditional sounding band piece. Easier low brass, good action in WWs and trumpets.
Fortis let me down in the past and Wildwind Overture is one I worked on with a really solid 6th grade class one year. But all the others I made 1's with my 1C Varsity Bands (mostly 8th graders).
Hope that helps!