Recording small orchestra help!?

I'd say ensemble at the auditorium, NT5s at some sort of a stereo technique (spaced, XY, whatever) from a distance (move the mics around and listen with headphones to see where they sound best. Get an assistant or a friend to help). Maybe you should do the strings and the horns separately. You can always add the "dry" home recordings later, if you feel like you need them.

Recording each instrument individually isn't going to result in any more "ambience buildup" than recording the entire ensemble at once. If anything you'll end up with less room ambience because you're close-micing them and getting a higher dry/wet ratio as a result. What I'd worry about is the orchestra recorded in a big wet space sounding out of place with the band recorded in a small dry space. Honestly what I'd do here is record in your home studio space where you (presumably) have more than two channels of preamp. Record them as an ensemble with a room stereo pair and use some close micing for sweetening.

thanks guys. im gonna record strings and horns seperately in the auditorium using xy stereo NT5 pair. then if it doesnt sound good, ill record it in a dead space and use artificial reverb to fit the song. The convolution reverb idea is a great one. Gives me an excuse to figure out how to use reaverb for this. Its coming up in a few weeks so ill post an mp3 when im done.