You didn't say whether this was pressure, or friction. Or both. You've gotten some sound suggestions so far, but here's one more: Encourage your friend to register for the forums and start asking questions herself. It's hard to figure out what's going on with someone else's butt by relaying questions and suggestions back and forth when the owner of the posterior in question isn't part of the conversation. Longtime cyclists, especially distance cyclists, are very comfortable discussing saddle issues - guess why? If she's embarrassed or feels uncomfortable discussing it on a public forum, there are plenty of forum members who would be happy to help her via PM's or email. I'd be happy to do that, and I'm sure Machka would be too, and probably lots of others. (If it helps, Machka and I are both women, with lots of long distance experience)
She might also read through the Long Distance forum for LOTS of discussions of saddle issues. And keep in mind that although men and women have different sorts of sensitive parts, both sexes have soft bits that aren't meant for sitting on and both have sit bones that ARE meant for sitting on. Most advice about how to find a good saddle, how to get comfortable, what kinds of adjustments to make, etc, pretty much applies to both sexes, so don't ignore the posts that ask about male issues. They might still contain useful suggestions.
One last caveat: We often tend to assume that women with saddle issues need a wider saddle, but that isn't always true. A saddle that is too wide can cause exactly the same problems, because the backs of the rider's thighs hit it when they pedal, so they're forced farther forward onto the narrow nose. So then the sit bones are not supported in exactly the same way that they're not when the whole saddle is too narrow. Or it means that the rider has to rock their hips to avoid that problem, in which case the nose creates a lot of friction and digs into soft areas. IIRC, a Trek 7200 is a hybrid that may come with a wide-ish saddle already, so that could possibly be a factor.
The size of the frame and height of the handlebars can also be a factor, particularly for a newer rider.