After three trips of Dining Plan usage, the answer to the specific question asked in the subject line of this thread, though, is "The best use of Dining Plan credits is to order food you LIKE; not necessarily food that is the 'best value'."
Seriously - so what if an entree is priced at $32, if it's something you won't eat, or will take a bite of and decide/realize you don't like the food?