Sorry,
To address your original post as well, I do not know much about Tech or Clemson, but I have visited NCSU, and would be more than happy to discuss with you the campus itself, the location in Raleigh, and other things. When I looked I wasn't interested in Communication Graduate work, so I can't speak on that specifically, though I did consider it in my first round of graduate searching, and it didn't appeal to me academically.
All are great schools with plenty of opportunities for TA/RA-ships. What are you most looking for in a program?