Hey, Steve,
I appreciate your explanation of your reasoning behind this. I can't say I agree with you fully, as I believe that in the case where the runner goes to second and THEN goes to third, I believe she went beyond the base to which she was protected. Thus, since she, in my judgment, went beyond the base I feel she should have reached had there been no obstruction, she'd be out. Since our games were called tonight (WOW is it windy out there!), I'll look further into this scenario.
Like I (and others) said earlier, this appears to be one of those cases where you had to be there, and two different answers do not necessarily have to be right or wrong. Sometimes, it still boils down to judgment, and whether you, as the umpire, judge that she would have made it to the base safely, minus the obstruction.
You may be right, I may be wrong, or even vice-versa. I still appreciate your excellent explanation, Steve.