No characters are ever "guarenteed" at a character meal, but your best bet for Ariel at a meal is Akerhus for lunch or dinner (but not breakfast). She is often at her grotto in the MK, and that is the best way to see her as a guarentee (without dropping a mint on a meal for a princess that may not show up). Its best to line up at the grotto a few minutes before Ariel appears - you can find her schedule - her line can get quite long. One the plus side, the grotto is tucked so far back that non-readers will never know she is back there if you want to skip it. My daughter is reading now, so I have to practice my "oh, my, they put in a spot to visit Ariel!" surprised look......