Yes, I know everyone else is talking about Grokster, but instead, I'll give you an update on what I just learned about cross-dressers and restrooms...at least in San Francisco.
Miriam Stombler told me that this issue is addressed by the SF Human Rights Commission. In San Francisco, individuals have a right to use the restroom consistent with and appropriate to their gender identity. The SF Human Rights Commission urges the use of single, unisex restrooms in places of public accommodation and employment.
I don't know about other cities, but Human Rights Commissions may be a good place to start one's inquiry.
For the SF Administrative code as posted on SF Human Rights Commission site ...