What I tried was 512 samples at 20 ms apart, and use a long variable to accumulate it into, so as not to overflow a 16-bit int. I'm wanting to make a IMU to take flying, mainly for attitude reference. These little sensors are very neat! I'm also using some ADRSX401 gyro/rate sensors, which are 5v devices, so the aref thing gets complicated.
If you are doing IMU stuff, there's good info over Spark Fun forum.
D.