Awesome! It was really good of Mark and Rachel to come back so you could shoot the photo again. Seriously, really works well--the skyline is centered and fills the horizon, they're looking at it from the side... I don't know how you could improve on this, other than having fireworks going off. Very nice composition!
if you use a flash whitebalance you should be able to get a nicer colour on the people, although the colours on the sky/city will change a bit, it will be less noticeable i think, and if you have a softer curve for the very bright bits her dress might work better