Really, you're going to be on roads or well-trodden footpaths for this trip, so I agree with those who say you don't need a hiking boot. You'll want something light but sturdy, with good cushioning and stability. And that pretty well describes the Endorphin ($90; www.vasque.com), a trail runner from Vasque that also offers lots of ventilation. Take a look as well at Salomon's XA Pro 3D shoes ($100; www.salomonoutdoor.com), which have excellent fit and well-cushioned but firm midsoles. Lastly, Montrail's Leona Divide ($100; www.montrail.com) are available in women's sizes and built on a woman's last, so the fit should be extremely good. These are a superb tried-and-true pair of shoes.
Also, I'd highly recommend you swap out the insole (the part upon which your feet directly sitit pulls right out when gripped at the heel) and replace them with Superfeet replacement insoles ($35; www.superfeet.com). Superfeet improve fit, add cushioning, and offer much more stability than factory insoles. They're a good investment in foot comfort.
And, be sure to take enough socks so you always have a dry change ready to go. SmartWool Adrenaline Mini Crew socks ($15 per pair; www.smartwool.com) would go well with any of the shoes above. So too would Wigwam Cool-Lite Mid Hiker socks ($9; www.wigwam.com), which have breathable, fast-drying Coolmax polyester in a soft acrylic blend. With good socks, and a good fit in the shoes, I wouldn't think you'd be plagued by blisters.
For more expert reviews of El Camino-worthy kicks, check out Outside Online's all-new Trail-Runner Buying Guide.