I second the XPS 13.
The 3200x1800 has revolutionised how I view excel sheets with tons of columns.
And yep, I get about 5 to 6 hours of usage.
Thanks. Coming from a rMBP, I definitely appreciate the ability to see more at once if needed and see crisper text in general.
XPS 13 seems to be a popular choice. I will ask her to definitely try it out.