Definitely consider USC! I'm currently pursuing a MPP along with a Certificate in Homeland Security & Public Policy. Our Center for Risk and Economic Assessment of Terrorism Events is a DHS National Center of Excellence. Feel free to PM me if you have questions. My program is very quant based. There's also the Trojan Network to lean back on
There's a dual JD/MPP program as well. Other than DC, LA is a great location for policy work in this particular field (i.e. RAND, intelligence agencies,LAX, Port of LA, Port of Long Beach , etc)