Essentially, it depends on what she prioritizes: her major (elite CS = UWash) or the rest of her college experience ( smaller, interactive classes, more personal attention, more flexibility in other academic endeavors).
As a young woman in CS, if she’s good, she’ll be hired, so the issue isn’t finding a job. It’s about what she finds most important.
An added layer is whether both are affordable - UW instate is probably half the cost of W&M. Can you afford W&M without parental loans, from income and savings?
Another layer is whether she got into the Honors College at UWashington, which would mitigate the 'small class size" issue in some gen ed classes.