It can vary widely. The topic itself is a bit fascinating if you read up on how the seating has evolved from ions ago. You might see the violas stuck in the middle, sometimes closer to the basses on the right. In film music it can vary even more, depending on the sound the composer, orchestrator, and conductor (of which all could the same person) wants to achieve.
Years ago I found myself lucky enough to sit at a Goldsmith recording session and I was distracted with so many other things that I didn\'t realize the basses were on the complete opposite end, the horns the same way, and about another half dozen or so interesting seating arrangements. The sound was just incredible though.. probably because it\'s Goldsmith where talking about here.. [img]images/icons/smile.gif[/img]
When I set up my sequences I prefer to pan the horns mostly left and the bones mostly right with tmpts in the middle (like the second example.) I just prefer the sound of it that way.
But, ultimately, as it\'s been suggested, you can really do whatever you want...or, more appropriately, whatever sounds the best.
Mixing makes a real difference too. In an orchestra, the percussion is typically set up with louder instruments in the back and softer instruments curing around more toward the front. (Which is partly why the brass is in the back. With brass up front that\'s ALL you\'d hear.) With a live setting that makes sense so you can actually hear the softer instruments. But when you\'re mixing a sequence, one can simply adjust the levels to get the sound right. And, with many recordings they alter the mix anyway...bringing out sounds (like marimbas) that you\'d never hear with a full orchestra blasting around them.