Scorps - I went through a VERY similar situation with my daughter and I'll tell you what I told her; If you put off what's already on the table to pursue a possible offer from the "big time D1", those other offers will be gone. What will you do if the big time D1 doesn't offer?
For what it's worth, my daughter had a time limit to accept the offer from the "lower" D1 program and was REALLY stressing out about it. In the 12th hour, she verbally accepted to the "lower" D1 and never did get the offer from the other school. And almost instantly she was relieved. And what made the situation even better was how truly excited she was with her decision, granted it was after it was all said and done, instead of "knowing it" like lafmom and many others have suggested.
I'm not suggesting lafmom or the others are wrong, my point is simply that the "Best Fit" may be right in front of you but you just don't realize it yet. You may not know it till later as was the case with my daughter.