Thirty miles in a day is a long ways. Most fit people can average around two miles an hour, maybe two-and-a-half. Three downhill. That's still a 12-hour walk, with no breaks! But good for you. I recommend something light, mid-height, supportive, with more foot protection than a trail runner. There's a whole slew of boots out there that fit that description.
A really good example is the Keen Targhee II Mid ($125). Really a nicely designed boot, with mid-height uppers made from nubuck leather and nylon mesh; waterproof-breathable liners; rubber toe guards; and a nylon shank that nicely balances stiffness with the need to have a comfortable gait. These boots have been really well received. They're built on a woman's last for good fit, too.
I also like the Oboz Yellowstone ($130). Similar specs to the Keen, with a mid-height, proprietary waterproof membrane, rubber toe, and heel guards, etc. I think they are a bit more durable than the Keens because the uppers consist of fewer pieces, hence less stitch to fell. What I have been struck by, in particular, is their extremely good grip. On steepish, wet trail descents they really grab. And the soles give good foot protection. Worth a look.
For something a little more exotic, take a look at the Lowa Bora GTX QC ($180). They have uppers of split leather and nylon, with an external "skeleton" of polyurethane for support without adding weight. This actually is a great idea. Years ago the French shoe company Le Coq tried to sell a line of boots with exoskeletons. I had some, and they worked fantastic. But they were so weird-looking they didn't sell. The Boras look pretty normal.
Remember, all boots within a given price range are more or less made from the same stuff. So what really matters is fit. Take the time to try on several different makes of shoes in several sizes. None of the shoes above require a lot of break in, but wear them around the house for a day to see if any hot spots or discomfort arises. Then, go out and hike!