The basic problem is that if you expose the faces properly, then the very bright background will be completely blown. In other words, the range of brightness in the scene is not just a bit excessive, it may very well exceed the dynamic range of your camera at any reasonable signal-to-noise ratio. The easiest and best way to overcome this is by using balanced fill flash. There are many tutorials on this on the web.
Trying to fix it in PS is like the proverbial "closing the barn door after the animals have left". You probably will be able to help matters out, especially if you have the raw data file for this image, but the results will never be as good / professional looking as getting it right in the camera in the first place. This is why you always see wedding pros using a flash, even in (err... especially in) bright sunlight.
PS - I see you are trying to post the raw data file. If you do, I will be happy to show you what can be done with it. In addition to the method suggested earlier using dropbox or a service like yousendit.com, you can simply zip the file, and upload it directly here. The forum's software will object and say that it doesn't recognize that file type, but just ignore the warnings, and it will upload. Anyone who wants to access it will unzip it on their end. Using this method, you won't have to down-rez it.
Since the OP hasn't uploaded his raw data file yet, I thought I would show the general direction I would take this image:
a) Fix the blown grasses using content aware fill, patch tool, etc.
b) Unless it's obviously and intentionally a high key photo, the background should be darker than the subjects, not lighter.
c) Fix the horrible cool and weakly saturated colors in many areas of the subjects' skin.
d) Fix the deep, chocolate colored shadows on some parts of the subjects' skin.
e) Try to recover at least some shading in the (almost blown) upper part of her gown.
f) A new, interesting sky should be dropped in, but, to be honest, I was running out of time at this point, so I just replaced the completely blown sky with a fairly monotone light blue.
g) Applied a slight blur to the background, and slight sharpening to the subjects. BTW, don't use the in-line forum preview to evaluate sharpening because it adds edge artifacts -- double click on the preview and look at it at 1:1.
h) One of the cardinal rules of composition in photography is "if it doesn't add something, get rid of it". There is absolutely NOTHING going on of interest in either the left or right quarters of the original, so I cropped these areas away.
i) Added a couple of keylines surrounding the image to bounce the viewer's eye back to the center of the frame.
Excuse my terrible masking job. I really didn't have a lot of time to put into this little exercise, but I just wanted to show the sorts of things I would do if it was my photo.
PS - Sorry about the bright blades of grass near the Dad's foot / lower leg. As I said, I only spent a moment on masking.
PPS - All of the time it takes to dealing with all of the above flaws in Photoshop, after the fact, is *exactly* why my very first recommendation was to "get it right in the camera", i.e., use a fill flash (which would only have taken a second to turn on, had one been mounted on the camera at the time of the photo).