Starting a texting "club" - best practices?

We have an opportunity to work with one of our sponsors to send offers via text messages.

If you are already using text messaging, I'd love to hear from you.

How do you promote opting into the text club? [print ads, email, facebook, etc.]

Are you working to offer consistent value across all channels - making the same offers via e-mail, texting, social networking sites, etc.?

I am concerned about email open rates dropping off - as offers are most often made via other [less expensive] channels - and email becomes simply "reminder" info.

If you're running a text program + engaging in social media marketing - are you sending less email?