Well, it saved this one! (And a few zillion others...)
[Sorry, i've edited this post about 5 times now, bear with me...]
In case anyone is curious though, here's a nice trick for a situation like this where I wanted to brighten up the mids without squashing the image or blowing out the highlights.
1. Duplicate the original layer and set the blending mode of the duplicate to Screen.
2. Select / Color Range and use the eyedropper to click on a dark black area of the image. Set the fuzziness slider to 200 and hit ok.
3. Making sure the duplicate layer is the active layer, hit Layer / Add Layer Mask / Reveal Selection.
So now you're using the new layer to brighten up only the dark areas of the image. And since the blending mode is set to Screen, it doesn't affect the dark information - thereby brightening the midtones. The layer mask makes sure it doesn't affect the bright highlights.
From there, there are many ways to tweak it, so I'll just stop now.