Lying between the full on symphony and the more rarefied world of the string quartet, there are scores of wonderful pieces for string orchestras of various sizes - Tchaikovsky, Dvorak, Elgar etc. 
 
Things you especially enjoy? 
 
Request: one at a time with a line or two about what draws you to the piece rather than lists. 
 
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Frank Bridge - Suite for String Orchestra 
 
This one has haunted me for 30 years or so. For some reason there are a lot English pieces for string orchestra, usually melancholy in feel. This four movement piece has that aching, autumnal feel, rich in melody.