I typed a whole thing up this morning before heading to the shop. Because I absolutely love wedding photography.
Take what I'm about to say with grain of salt.
The first image you posted does absolutely nothing for me. B&W in my opinion is used to save a shot that was trash. Or to change the emotion of a photo. In this photo there is no emotion that I'm feeling that was worth the switch to B&W.
The first photo looks like it has 4 PM sun in it with the glare on their foreheads. Where you second shooting or a primary? I would have dropped my aperture lower then 7.1 for that shot, not matter where I composed from. Always take into consideration of whats in the foreground and background in when you compose. This changes slightly if your shooting a portrait where you want flower or foliage in the foreground of the image. You dont want sticks in their heads or face, or trees growing out of them. Break the lines, move up and down, and to the sides.
Your second shots posted. Like Tim has stated, if your focusing on the flower, which I assume you are, then focus on the flower. You don't have to include a face in a photo to make it something worth keeping. Find the details, think about wedding photos you've seen, and what you haven't seen. I would have got right in on the flower and her hands. I would use it as a filler photo in a clients album.
Out of the pictures you've posted, on my shop monitor, they are either blown or underexposed. What setting are you shooting in, with your Nikon? 300mm at 2.8 iso 800 with a 1/2500 shutter is cookin! Out door wedding you shouldnt have to be in iso 800.
That ring shot has too much going on. The papers on the right are distracting where my eye is supposed to go, and I am wondering what they say. Im also looking at whoevers arm is holding them. I know, your cant help or quite control what happens in wedding photos, but still refer back to what I said. Move around and think about your composure before you push that button. Dont be afraid to get closer.
My biggest complaint on what you posted is, I want to see color!
Friend Will in New York, is a foreground and background shooting. He has the asian market wrapped up. Check him out. http://www.william-chang.com/