[pk_hat]

i think it comes down to the sound source itself. it's true, most of us reach for string patch #___ and just play along. it's often a warm and rich sound but we can all agree that if you want realistic strings, a rom based synth won't cut it. I think some are very good (Roland XV series), but for better strings and other emulations, a sampler fits the bill.

Either way, a good thing to do is to lay down your tracks separately to bring more realism.
ie. have your double bass, cellos, violas and violins on separate tracks, panned and processed individually with a healthy dose of RenVerb and you'll be amazed at how much better it sounds than a combo string patch.

More tedious and requires a bit of thought in placing the instruments in the right key zones but the results are astounding.

For even more realism, a sample library of strings (Garritan) would stomp over anything else, albeit an expensive alternative.

if using Midi for strings, it's good to have your mod wheel assigned to the 'expression' or 'aftertouch' parameter, so that your long sustained notes don't sound so static.