Let's begin with accessories. I suggested she bring some neutral jewelry that can dress up an outfit, but can also be worn more casually. For shoes, I thought she should bring both flats and sandals (maybe even some flip flops, depending on your style) to give you a couple different options. And finally, a scarf (for the possible chilly evenings in Seattle), a cross body bag (so much nicer than a regular handbag when traveling - I wish I had one on my recent trip!!), and a military style anorak (I'm obsessed!!).
For tops, I suggested bringing a mix of tanks, short sleeve tees/shirts, and long sleeve tops that she can mix and match between the bottoms (see below). I tend to stick to similar colors so that everything kind of goes together and coordinates well when trying to wear things multiple ways, but it's really up to you and your personal preference. I would also suggest bringing (or wearing on the plane) a lightweight cardigan to throw over the tanks when it gets chilly.
For bottoms, I thought a couple different pairs of pants (jeggings are great for traveling because they are super comfy!) would be best. The lighter pair of denim could be rolled up for a different, cropped look. If you don't like the boyfriend shorts, any denim shorts would work in whatever length you prefer.
And finally, a couple of jersey dresses which travel well (they don't wrinkle too easily) and could be dressed up or down.