Did you intern anywhere? That will be helpful as the market for PR and Ad Agency reps is competitive and they rarely hire without experience.
A link to a thread about the subject:
Advertising Agencies in NC?
One helpful tool is to network with people who sell airtime or space in print media and find out what ad agencies they work with. Honestly, when I was in broadcasting, a lot of our ad agencies who placed with us were out of state. There are some here though.
PR/Marketing Agencies I would try:
Lyerly Agency (very cometitive to get a job though)
Wray Ward Lasseter (also competitive)
Also, there are some agencies that specialize in NASCAR marketing.
Link to PR/Marketing Job Bank:
PRSA Charlotte :: Job Listings
If I can think of more, I'll post them.