I think you can take a run at all those schools. The 680 GMAT will be somewhat of an issue at a Duke or Darden, just because they can afford to be so selective, but by and large you are "in the game" with that score. In my experience, if you are 670 and above, they will read the file and that's when you can tell your story.
Indeed, the tale you will tell is one of newfound maturity, focus, and discipline in this next go-round of college. I actually don't think that many schools will worry excessively about the extreme disparity or even what happened way back when. Where your GPA hurts you - more than the way it happened - is the raw number. Some schools are going to bite the bullet and absorb a sub-3.0, some are going to wrestle with it, and some just won't touch it. It sort of depends on how compelling you are otherwise. We've worked with a lot of low GPA candidates in the past and it basically goes like this:
- Ramp up maturity throughout
- Highlight transferable skills, goals, and school fit better than your peers
- Apply to more schools than normal to give you some safety in numbers
That's generally the way to handle it. I think you are in the right range of schools - you just have to apply to enough of them, and do it well enough, and I think you can have a shot.
Hope this helps.