Rather than a single measurement, focus on behavior and balance: if the dress rides up when you walk or sit, requires constant adjusting, or lacks any balancing element (coverage, structure, or dressy fabric), its more likely to read inappropriate for a wedding
If youre between sizes, Id personally think about what you want from it: if you want it more fitted and sleek, sizing down can work (as long as it doesnt pull)
McCalls 6102: View D, shift style, 2 bust darts, pull over, large size range, neckline facing McCall's 6465: view E, slip over, sleeveless bias tape arm holes, loose A line shape FINDING YOUR SIZE: READ the measurement section for the company that you are buying the pattern from
As for your pants, the plaid jacket/boot combination fits particularly well with a pair of blue denim or black denim
They are really fun to twirl in
Plus, the ruched waist is universally flattering, so your gals will look AND feel their best all day long