First of all, none of my kids are 读ing 藤校. So, I hope I could be objective here.
A person's success is really determined by him/herself's motivation and drive - the internal factor. Where they attend University is only on external factor.
That being said, one must consider these other factors between 州大 and 藤校.
1) not all states have excellent 州大.
2) the % of getting full ride at excellent 州大 is much smaller than get into 大藤
3) due to the budget cut, the cost of attending some 州大 is coming up. there is also possiblity that you could not get the class you need so 州大 may take you 5 years to graduate
4) 州大 graduates have only regional support.
5) In US, the mean family income is around $55,000 a year. Most of the people here are upper to super upper 中产.
I could go on and on about the Pros and Cons. But it is your money and your kids.