Ditto on arm rest.....she loves it.
Also, got a side pouch for camera, odds and ends.
Drink holder, plus added a gps bracket so she take care of any extra navigation (looking for poi's, hotels, etc) while I try to stay between the lines.
Ditto on the ditto. She will also be able to take naps on long rides. You'll never know it untill her helmet bumps the back of yours. That's usually my que to ease up in the curves so she can enjoy her nap.
A taller set could be fabricated easily enough. ANy idea how much higher she would want? If you get too high it'll make getting in the saddle more difficult. The armrest are a good solution, they swing out of the way when entering or exiting. Plus, you could tie a rope betwixt them and she can't fall off during a power nap