HI Suzibob! I'm new here as well.
Have you considered participating in a summer fellowship that is tailored to the study of public policy. The Public Policy and International Affairs Fellowship is one I STRONGLY recommend. The application is not due until November 1st, so that gives you plenty of time to consider it should you be interested. It's for rising seniors which makes you the perfect candidate! As a participant, you're required to attend a Junior Summer Institute at either the University of Michigan, Princeton, Carnegie Mellon, University of Maryland and the University of Berkeley. The program pays for your transportation to your host institution, housing, meals and a small stipend to help over the summer. They even fund a GRE prep course through Kaplan! I participated during the summer of 2010 (I'll refrain from naming my host institution for the sake of anonymity.)
I'll be applying to MPP programs for Fall 2012, but have a few friends who have just started in programs this year. All of them enrolled in graduation school straight from undergrad (K-MPPs as we call it) and had tremendous success during their cycles. PPIA follows you throughout the entire application process, as it provides you with the prerequisites for many of the MPP programs out there during the Junior Summer Institute, such as econ and calculus. It's an intense program, but the evaluations you receive at the end of the summer from your professors will take the place of one letter of recommendation at many of the PPIA member schools. Those include Harvard, Princeton, Yale... the list goes on. These member schools often have hefty financial aid packages specific to fellowship like this and even waive application fees for us (something I'm sooooo grateful for right now.)
I have a friend who just started at the Kennedy School and says that of the handful of other K-MPPs there, they were all participants of some fellowship similar to ours (Pickering, McNair, etc.) None of them had full-time work experience prior to enrolling. Their fellowships played a huge role in their admission cycle because being accepted to and participating those programs show a level of dedication and passion for public service that is hard to parallel. He also had little public interest experience prior to PPIA and was one of many in my cohort who did not have a political science/government major. I also have a friend at Carnegie Mellon and two at Berkeley and they all share similar stories in regards to the backgrounds of those entering straight from undergrad. All four of them are fully funded with a stipend, as well.
When you get a free moment, check it out for yourself. http://www.ppiaprogram.org/programs/eligibility.php If you have any questions let me know!