The following are the security frequencies for select malls in Virginia, DC, and Maryland. I didn't bother to list the housekeeping and individual store frequencies, as this would make the list a bit unwieldy. For the full list of everything I've found at the malls, check out the individual county pages.
461.8875 [203.5] Ballston Common
451.5250 [ d411] Dulles Town Center
464.1250 [ ] Fair Oaks (MOTOTRBO)
464.4375 [ d074] Fashion Centre at Pentagon City
464.9250 [100.0] Landmark
462.4000 [110.9] Leesburg Corner
461.0125 [100.0] Manassas
464.9250 [ d612] Pentagon Center
463.6000 [ d723] Potomac Mills
464.3250 [ 77.0] Springfield
461.9875 [ d054] Tysons Corner
464.8250 [ 94.8] Tysons Galleria
452.9250 [141.3] DC USA
461.3250 [ d411] Gallery Place
463.9500 [ d612] Georgetown Park
468.5625 [ d606] Mazza Gallerie
464.5750 [ d346] Union Station
461.9750 [ CSQ] Boulevard at Cap Centre
152.9225 [ d074] Bowie Town Center
464.2750 [ d606] Chevy Chase Pavilion
461.1125 [162.2] Columbia
464.7000 [ d423] Lake Forest
463.7625 [203.5] Montgomery
464.3750 [ d032] Prince George's
464.6250 [ d023] Wheaton
464.8250 [151.4] White Flint