The Bride	The Medieval women's fashions were usually long and flowing with somewhat fitted bodices that ended in trailing skirts and had long, draping sleeves. Contrast this with the Renaissance style of full, round skirts and tight bodices with long, puffy sleeves. Both styles often used similar fabrics -- heavy velvets, tapestry, brocade, heavy satins, wool, and heavily embroidered materials. Lace was not as common as in later years. Metallic elements and beading were popular. These styles lend themselves very easily to a gothic Medieval/Renaissance bridal gown. The draping angel sleeves of the Medieval era are already found in gothic clothing, and the tight Renaissance bodices require corsets, which many goth gals are already familiar with. And the heavy fabrics look rich and elegant in dark fabrics.
The Groom	Medieval and Renaissance men's clothing could be very dramatic, and usually involved the gent wearing boots, hose, short breeches, and either a long, loose tunic or a shorter, fitted doublet. All would be in the same type of heavy velvets, tapestry, brocade, heavy satins, wool, and heavily embroidered materials as women's clothing. Men's Medieval tunics might have long, draping sleeves, while Renaissance doublets could have similar long, puffed sleeves. All parts of the outfit could be elaborately decorated. Both Medieval and Renaissance men wore jewelry too, including heavy chain necklaces, large rings, and a single dangly earring. To top off the look, a well-dressed man might have a cape and a sword. For a gothic Medieval/Renaissance wedding, a man can dress quite dramatically. Heavy, lush fabrics in dark colors, perhaps with metallic accents, would work beautifully in any of these styles.
Setting	If you can find one, an English Tudor style building is the ideal setting for this type of wedding. The next best setting is the local Renaissance Faire -- these can often be quite good deals because the Faire can provide the setting, food, drink, and entertainment for a package price. Other appropriate settings are rustic homes, B&Bs, and buildings with lots of dark wood detailing (especially Arts & Crafts style buildings from the early 20th century) or outdoor locations such as a wooded glade.
Decorations	Greenery such as ivy and pine boughs add a Dark Ages flair. Bouquets of herbs are very period. Heraldic crests and banners have a royal touch. Heavy, ornate serving ware and candle holders set on tapestry table runners would look perfect too.