Thanks for the thoughtful responses, guys. I was on a similar wavelength -- since the rankings really are more of a range, then +- 5 probably isn't as much of a gain/loss as having or not having that Ivy status. And yes, that connection building could be huge...
werd, Re: Berkeley vs. Harvard, just remember that research interests can change/develop over time, so the initial question of "is this a perfect fit" might not be as relevant as "is this a good enough fit that I'll be happy". Not much to add on top of what ghanada already said. It comes down to how much the difference there is between the Harvard fit compared to the Berkely fit. But man, you've got some good options!