There is much useful information about careers in public service at the website of APPAM (Association for Public Policy and Management): http://www.publicservicecareers.org/
You’ll find tabs for “Find a Job” (and you can look at jobs that specifically require a BS, MS, or PhD), Career Advice (including advice on finding internships), “Why Public Service,” and information about graduate policy programs.
As APPAM notes, “We define the ‘new’ public sector as: Government, Nonprofits/NGOs, International, Consulting and Education. Many people today move from one sector to another.” At Georgia Tech, many BSPP graduates have found employment in the private sector, as well. This website should help you think more strategically about your career plans.