Hi, Jenny.
You've already gotten a nice, intelligent range of responses to your excellent question--but, what the heck, I'll toss in my two cents.
I'm a non-directed donor who has still not gone public. However, as a sort of compromise, I've encouraged the docs I've met during my (long) approval process, plus the volunteer organization that matched me up with my recipient and shepherded me through the process, to invite those considering donation to contact me for advice, support, etc. Over the past three years, I've gotten several calls from such candidates and, largely thanks to what I've learned here on LDO, I was able to pass along some useful information, tips, and real-life experiences. Beyond that, I think I allowed that organization to use my initials for a newspaper ad promoting donation (I think they wrote that the full names of signatories were on file with the organization, or something like that). So it's worth recognizing that it's not necessarily an all-or-nothing proposition. And, of course, you can do other things for such organizations, such as helping draft copy, stuffing envelopes, making connections, some quiet fund-raising.
Some of my reasons for not going public are purely personal. On the other hand, it's also true that I've sometimes been a little uneasy with the hype that certain organizations and media stories generate about donation. Yes, I'm thrilled I was able to donate; it's a highpoint of my life. But: there actually are some medical risks; there do exist some limitations in our knowledge of long-term effects of donation; some people do suffer unpleasant medical complications; others report serious family or marital conflicts surrounding donation. Sometimes, the hype can sort of soft-pedal such issues, while trumpeting how wonderful donation is.
I guess one has a bit more power to negotiate exactly how one's name and experiences are used when dealing with an organization, but with a newspaper, magazine, or broadcast outlet, that's probably much less true.
Whatever you decide, good luck!
Be well, Snoopy