Except for all but a handful of schools which conduct interviews (many don’t. Probably half of your “top 30” list doesn’t), the interviews count for next to nothing. Unless you do something absurd (spew something bigoted, stab them with your water glass) you’ll be fine.
Have a look here:
http://talk.collegeconfidential.com/admissions-hindsight-lessons-learned/246098-the-thread-for-college-interviews.html