While nice in thought I think it means a whole lot more to receive the smile, hot cocoa and thanks a day after they do something that was appreciated rather then because it is "parents appreciation day". when it just gets lumped into a specific day and all parents get the same regardless of them being incredibly great or incredibly annoying to work with then it just loses some meaning.
I would save such gestures for parents when they have shown that they trust, respect and appreciate you.