VIK, I have to say that the choice of saddle and the position of the bars has been critical to my wife's comfort. Brooks Leather saddle?? I gave that up for myself a long time ago. I coudn't imagine my wife tolerating one of those for 100 yards! If you are going to spend on anything...don't skimp on her saddle. Even with a shockpost, a stoker will get beat up more than on a single for a couple of reasons. One...she doesn't see bumps coming and no matter how diligent you are about calling them out, she will be seated for some of them. Two...more time spent in the saddle-not standing. It is also a fact that the ladies have different comfort factors, like friction areas that we don't have. This made, in at least our case, the position of the bars important. If they were too low, she would get too much seat intruding on her privates, and if they are too high, a sore butt! Being that my wife is a bit tall, it was a challenge to get the bars up high enough, because it is limited to the captains seat post height. I had to find an adjustable angle stem for this purpose. OVAL makes a really nice one.
The saddle that she always comes back to is an old Terry gel ladies saddle. This works for her, but saddles are very personal and it is best to try alot of them. I managed to buy some on ebay for pretty reasonable cost and the ones that didn't work out, were subsequently sold.