D-VIs are awesome, I don't have one but I've tried one out and i've wanted one for a while...
"standard tuning" would be ADGCEA (lowest to highest)
Daniel Ho plays his tuned to GCFCEA (I think he calls it C-Kilauea tuning)...the advantage is you can play the bottom 3 strings just like any other uke and the open top strings give you access to the I, IV, V bass notes in the key of C