Kona Cafe for breakfast is always good - it's a vacation tradition for us.
Sci-Fi is a fun place to eat at least once, but don't go there expecting great food just go for the experience. Order burgers and shakes and sit back and have fun.
I went to Garden Grill for lunch (btw pretty much the exact same thing is served at dinner as well and it's a lot more money then lunch) However it was so yummy, everything. At first my friends were all kind of hesitant if everyone was gonna like it but omg we made piggies of ourselves lol. We seriously devoured the Potato dish in minutes. I highly urge you to try it if you can, it's so good.