The horns are always front/center .....guys with amps (bass, guitar, etc) are behind them , spread out like a typical 'amp wall' about 10 feet... somewhat even with them, though slightly in front, are the piano/keys and the drummer/vibes, so something like this
Stage lip center
Stage lip left Stage lip right
H o r n s
Drums piano/keys
Bass amp Guitar amp
the drums, horns, and pianos are each about 6 feet from their respected stage lips