As I've hopefully proven above, the band has many nice free options from piano to guitar to drum and more. The Orchestral section is more problematic. Fortunately we have two fairly complete orchestras and a couple solo quality instruments. The orchestras are the Sonatina and the Iowa.
The Sonatina has a lovely consistent sound and is quite nice for sections or ensembles. It uses a very small memory footprint, in fact at 600 megs or so it is smaller then many modern single instruments. The downside is that it doesn't work so well for featured solo instruments as there are just too few samples, usually every third note is sampled with one velocity layer. It becomes really obvious that you are using the same sample over and over again.
The Iowa is almost the reverse. It has only solo instruments, though we can get ensembles through scripting. The sound can be a bit rough, but since I've removed the roughest samples and digitally tuned almost all the samples (the lowest tuba / bass notes confounded my tuners), I think it has some very passable brass and woodwind solo instruments. With the tuning it sits pretty well with any orchestra tuned to 440.
The MSLP Flute and Trombone are very nice solo instruments. They are heavily sampled with many articulations and a very smooth sound. The Pablo Trumpet is also a pretty nice multi-sampled instrument.
The string section is quite well served. The solo violin and cello work well out front and the double bass has a great growl to it. The viola involves using a shell and downloading Philharmonia samples. I would just use the viola included in the Kontakt factory library.
That of course begs the question why not just use the Kontakt factory library (and don't forget the legacy instruments)? For me that is like asking why buy another book or game or dvd. Variety is the spice of life or in this case music. If everyone else is using the Kontakt String Ensemble, Cello and Flute, why not mix it up and use toys other people aren't play with or don't even know exist. Plus in this commercial world of ours, it is kinda fun to mess with the rich folks minds, don't spend money and still get new toys. They haven't made that illegal... yet.