This is how I see it:
In sentences were there is a comparison "like" should be used when comparing nouns and "as" should be used when comparing actions.
(This is what Kaplan says in the Verbal workout).
In sentences where there is a list of examples, if you are given a choice between "such as" and "like" preceding the list of examples, always go for "such as". (From my personal experience with GMAT SC).
Feel free to comment on this...
Martin.-