what the heck do I wear to a black tie wedding?

I am going to an out of town wedding in St. Louis in Late May. The wedding is at the four seasons and states Black Tie on the invite. I don't know any other women attending this to ask what they are wearing and I am torn between floor length or dressing knee length since it will be very hot. Also there is a brunch the morning after. what do I wear to the brunch? HELP pleaseI do best with pictures so I'd thought I would give you some:Black Tie Appropriate:http://www.lordandtaylor.com/eng/WomensApparel-Dresses-LongCocktail-Beaded_Empire_Waist_Halter_Dress-lordandtaylor/54478http://www.lordandtaylor.com/eng/WomensApparel-Dresses-LongCocktail-Floor_Length_Beaded_Halter_Dress-lordandtaylor/54477http://www.lordandtaylor.com/eng/WomensApparel-Dresses-Empire_Waist_One_Shoulder_Gown-lordandtaylor/54080http://www.lordandtaylor.com/eng/WomensApparel-Dresses-LittleBlackDresses-Square_Neck_Sleeveless_Sheath_Dress-lordandtaylor/54446Not Appropriate:http://www.lordandtaylor.com/eng/WomensApparel-Dresses-ShortCocktail-Empire_Waist_Chiffon_Strapless_Dress-lordandtaylor/54095http://www.lordandtaylor.com/eng/WomensApparel-Dresses-ShortCocktail-Bow_Detail_Bubble_Halter_Dress-lordandtaylor/54558Brunch Appropriate:http://www.lordandtaylor.com/eng/WomensApparel-Dresses-Sleeveless_V_Neck_Dress-lordandtaylor/54356 (with cartigan preferrably)http://www.lordandtaylor.com/eng/WomensApparel-Dresses-Ruched_Printed_V_Neck_Dress-lordandtaylor/53025Hope that helpsAlso, since it is black tie, its probably evening wedding so you could always get a co-ordinating sheer wrap to put around your shoulders in case it is chilly outside at night or inside the venue. ( I know they crank up the AC if there is a lot of dancing going on.)