The only thing I am trying to figure out with what Page said is the angles. For most of my concert taping setup I have run the same patterns and setup.
Look at the Williams SRA curves and play around with that. You'd be surprised just how little spacing/angle is needed to achieve "stereo" when you're non-duplicated sound L/R is at an orchestral angle of around 150 degrees. Lee's taken care of the long form explanation on that as well as the little things you can do when mixing sources that are neither spots, nor contain the same information (e.g. mics along the front row but focused on different sections). As he notes, spot mic mixing is a different ball of wax but in this environment, it sounds like you'd only have to worry about your solo mic being an issue. The only thing I can add before the show on that topic is to keep in mind two things; what do you want to record (the stuff that is right next to the mic) and what do you not want to record (everything else). Now aim the mic in such a way that it's natural rear rejection works toward your advantage (sort of like a virtual audio gobo).
oh, and Lee's right, the two of us approach a problem in vastly different manners but try and shoot for the same goal. I prefer a semi-coincident base/main with flankers for the edges. He is more open to the flankers/spaced pair being the main sound with a center channel to help glue stuff together. Both will definitely accomplish the job, but they would sound different and it's a mixing preference at that point. There isn't a wrong technique
per se in this, just some factors in setup requirements that would cause us to favor one over the other. Those are some of the things we've tried to point out (how they will be setup, what the room is like, any soloists who will come to the front of the stage, etc).
... They are a 44 piece setup. ...
That said, it wouldn't surprise me if they used all of the space that's practical, so if you need to visit the auditorium ahead of time you can do a rough measurement of the width.
I've done a couple at the local high school's auditorium and the HVAC is so noisy much of the mic placement considerations are a waste of time. Be ready to accept weird conditions and EQ the snot out of it later if necessary. I know you want to do your best but he's gonna be thrilled with whatever you deliver.
Both are valid points. The first one is why I highly suggested seeing if you can see a soundcheck or practice session. At the very least go by and walk through the space with the director and take lots of notes.
The second I've been burned by before as well, and yes, he will likely be thrilled with whatever you send out as long as it's not a total loss. I've done big band engagements and people were tickled pink with a result that I thought was lack luster, and I suspect this sort of gig would be the same way. It's not an excuse to slack off or plan poorly, but don't panic over the mixing element. If nothing else, a sample track can allow us to offer advice later.