From Seattle taking the "slow" way, I'd probably take US Highway 12 all the way across. It parallels Interstate 94 all the way across to Indiana, but is mostly just a 2-lane highway that goes through all the small towns the interstate goes around.
There are a lot of national parks and forests to visit on the way- Mount Rainier, Grand Tetons, Yellowstone, the Badlands, Mount Rushmore- as well as some nice cities, such as Minneapolis and Chicago.
The entire US military is cutting back right now, but if she's interested in becoming a pilot, she may have options with another branch, such as the Navy or Army, though the Army would train her on helicopters first. Not to say it would be possible or easy, but it might be worth talking to a recruiter from one of the other branches.
Other than something homemade, some kind of local specialty product is always a good gift- when I went to Taiwan, my wife and I brought honey and jams from Wisconsin, where we lived at the time, and it went over pretty well.