Only one night in Rome and no dress clothes
In four days I will be in Rome for one night wearing khakis and a button down short sleeve shirt. If you had only that one night and no suit where would you eat?
There will be plenty of fresh seafood on the rest of my trip, but other than that I don't care if I eat a pizza or truffles. Is there a "don't miss" foodie experience for me?
It's awfully hard to tell you where to blow your one shot, but I can tell you not to worry about the suit. Rome is not a dressy city, and there are no maitre d's policing your wardrobe, except at La Pergola and possibly the Grand Hotel and a couple of others. I regularly see very casually dressed Italians at Il Convivio and Agata e Romeo (not that I go to such places very often), and either of those would be worthy of your single chance. If you want someplace more traditional, there is Checchino dal 1887, but it helps to like meat. Piperno, in the ghetto, is another idea. I'd skip both pizza and truffles.