From Ilan's Tumblr blog:
"I Bought the Eastwest symphonic orchestra GOLD plug-in that is worth every penny and I always manage to create a great top line using it. It is by far the best plug-in for doing string lines."
Here's a list of most of the additional plugins and things that I generally use in my production:
Waves Gold bundle (an awesome set of mixing plugins)
Waves TransX (my favorite transient shaper plugin)
EWQL Symphonic Orchestra Gold