Those flash chips look nice and easy to use. They are fast, with an auto address counter, could be very useful in a separate circuit to speed up sprite drawing. They would be nice on the shield for simple storage also. As I'm writing an 'animation capable' library for the screen, I will definitely look into testing one out.
Regarding the RD pin:
How would you connect the pins? Would you connect a digital pin on the 3.3v side or RD side of the resistor? Or maybe disconnect RD completely from 3.3v?
I'm thinking maybe an NPN on the RD side to pull RD low, the 3.3v sets the high.