It's a terrible conundrum, but one of the things I'm learning with websites is that the better you know your audience, the harder things get.
What do I mean? Take for example an gallery that wants to engage with a teen audience. How do you balance lolcats and unicorn memes with the organsational info you want to deliver teachers, parents, sponsors and other galleries?
The Walker Art Center's solution is characteristically elegant and playful. Go to the teens page on their site, and you're presented with two sets of info ("the business side of things" and "the play side of things") each with its own design (let's call them art gallery chic and MySpace). A yellow band bisects the page, and by sliding it you can choose for yourself: admin-type stuff for adults, or glorious teenage tumult.
The yellow band solution is genius. It fulfils both audiences' needs: teens can avoid all the institutional information and shape their own experience, while people interested in other aspects of the Walker's work with teenagers can get the information they want. But, importantly I think, both spheres are contained in the same place and accessed from the same start point. You can read about the way the Walker developed their approach in this paper from the 2008 Museums and the Web conference.
Actually, to call it "admin-type stuff" undersells the info the Walker provides for galleries looking to build their teenage audience. The Walker's work with teens is mediated through WACTAC, their teen council - a group of teenagers who meet weekly to "design, organize, and market events and programs for other teenagers and young adults". The Walker has a really useful Teen Programs How-To Kit (warning:PDF) that describes their learnings from different tacks they've tried.
p.s. you've got to love the pink unicorn