Last year I hit the SuperTarget (just before they put in the expanded grocery section), Costco, and Safeway. Since it was just me, I didn't need all that much, so all I got at Costco was some POG juice and a pineapple. I got few things at SuperTarget, but did most of my shopping at the Safeway. I signed up for the Safeway card and most of the stuff I selected was on sale. Unless the grocery section has greatly expanded SuperTarget's choices, I just plan on shopping at Safeway the next time I go to Aulani. It would have been much more convenient for me to have just shopped there rather than running to all three places. (Although I have the say that the POG juice was a really good bargain at Costco, and I could also get my hot dog and soda there for $1.50!!)
I stopped at that WalMart in Kapolei the last day I was there to pick up some souvenirs, but I noticed that they don't have much in the way of groceries. It's definitely not a Super Walmart. I did get some killer deals on beautiful Hawaiian calendars that worked great for the people back home! For my macadamia-related treats that I brought home, the best prices I found were at Costco.