Here is USC's freshman profile for this year: http://www.usc.edu/admission/undergr...e2013FINAL.pdf
Your SAT and ACT are firmly in the bottom quartile of admits. Keep in mind that USC admits a lot of athletes and artsy people (film, music, etc.) with low stats.
3.59 is definitely below the mean of enrolled and admitted, although about average for applicants. This should tell you something.
Because you are statistically inferior, you need to write a stellar common app essay and a supplement that clearly demonstrates why you want to go to USC. What major/school are you applying to? Why?
As far as UCSB, your SAT is slightly below average but your GPA firmly below. Your ECs are strong (probably much stronger than the average SB student to be honest)... UCSB really is not that selective of a school. I would expect you to be close as long as your personal statement is good.