I don't think vinaigrette is considered a small sauce. I would try to show a few things in your exam.
1) Perfect cuts, preferably a variety of cuts with a variety of vegetables as you have learned. Try not to repeat the same garnishes or vegetables in different parts of the meal.
2) Sound technique. In otherwords, make sure your brown is the correct brown, don't overdust your meat, dry your lettuce properly.
3) Show a little bit (not too much) ingenuity. Perhaps a third sauce derived from a mother sauce but not a classical sauce, or a chicken blanquette instead of a veal blanquette.
4) Proper proportions. 6oz of protein for the entree, 8-10oz for the whole dinner is considered just right these days.
In general, if you're going to do something, make sure you do it well. Demonstrate as many basic cooking skills as you can. If you're going to filet a sole see if you can work in a quick stock from the bones.
Don't forget your names and what they mean. Since it's classical, the names are very important in the sense that they name the entree, specify the garnishes, and have historical significance. For example, you cannot have Chateaubriand without potatoes chateau!