Hi,
I am using SST25VF016B flash (2 MB) with DUE and I am quite happy with it. I am writing a small Lib to interface with it. You can find it here: http://luca72.xoom.it/td5mapsuiteweb/archive/FlashLib.zip. It is not yet finished, but quite complete. It is pretty fast (I drive SPI bus at 42 MHz, DUE half speed) and you can address it as if it was an EEPROM.
Luca