@twogirls makes an excellent point: even at top LACs you have to put yourself out to get the opportunities. Both schools will definitely have more opportunities than she can ever take advantage of- and will also have a lot of very motivated students going for them.
Both neurologically and circumstantially your daughter is about to do some serious growing, so what looks daunting relative to where she is now may be just the right amount of challenge for her when the time comes.
In case it’s not coming through- I do get how hard this is! but your core question was ‘is WUSTL worth $175,000+ more than UNC-CH’ and imo, unless you can write the check without compromising anywhere else, the answer is no.