In style accompaniments the strings often play Pad-like floating voices.
As we have a limited number of keyboard channels, we will have to select one of the String Ensemble voices for this purpose.
By choosing this approach we are not able to program the string instruments individually. Therefore select carefully the right ensemble voice, and add some kind of dynamics to the accompaniment.
Variations in velocity between the style parts are one way to add some dynamics to the strings. Another method is gradually increasing (crescendo) or decreasing (dimininuendo) the volume (MIDI Expression Controller) within the part.
The floating pad voice may tend to be quite monotonous. Therefore let the strings have a break now and then. Or changing between legato and staccato parts will also be effective.
If the strings play more Phrase/Riff like accompaniments using fewer (or just one) instrument we have of course better possibilities for programming the instrument accompaniment.