There was an article in March 2011's edition of Computer Music called "Keeping it Real": Program realistic strings, guitar, winds and brass.
Find more stuff here:
http://www.musicradar.com/computermusic From my own experience, using the CAL files "Random Time" and "Humanize" goes a long way in this respect. Also, learning how the instruments are played, orchestrated and their inherent limitations allows you to program more realistically (e.g. no drummers with three feet and four hands, or strings playing in ultra-stratospheric ranges!!). The instrument you use is also critical. The best results I've had have come from my recent purchase of NI Komplete 7 especially MM-Scarbee Bass (which is unbelievably realistic when you get to grips with it) and the Kontakt Sax and Brass for Kore 2/player. For Drums, XLN Audios Addictive Drums and Toontrack's ezDrummer plugins are excellently modeled. Some of Session Drummer 3's presets are not too bad either but don't have the depth of dynamic range for my liking (the free Ocean Way download that came with Sonar 8.5 is, however, a little closer to what I like). There are some very good presets in Dimension Pro for Acoustic bass, especially in the new expansion pack 3 (which is a free download for registered members from the cakewalk store)
Hope this helps :)