"The Great Locomotive Chase" or "The Great Steamboat Race" by Smith. They are very similar but both fun.

Any movie theme. Add props. Our kids put on pirate hats when we played a pirate song. We put on lei's when we played Moana. We once played Frozen and had two girls (not even in band) dressed up as the two princesses and walked around handing out candy the whole song.

Halo 3 arr Michael Story. Kinda easy though. but maybe instead of one fun song grade 3, play two or three easier fun songs.

"Solo Flight" by Neeck or "Classical Rondo" arr Glover would enable you to feature one to four kids.

I think Holsinger's "Havendance" is fun.

Are there any high school arrangements of PDQ Bach?