I have CoPilot Premium USA and CoPilot Truck. Both work reasonably well, and maps are all stored on the device. You can download the entire US map, or just selected regions. The northeast maps that I'm using are under 300MB.
Be aware though that without a cellular connection, devices with only A-GPS won't necessarily work too well (or at all) when trying to determine/track your location for navigation. Even with maps stored locally and routes calculated locally, a cellular connection may still be required to make navigation usable.