“Relationships” is a pretty big topic. Narrowing down the type (doctor-patient, teacher-student, parent-child, spouse-spouse, etc) might help you identify likely sources. Also add an elevator speech to your query letter/email, outlining what the book will be about, how it’s unique, why you’re writing it and what you hope to accomplish. Are you paying your contributors? If not, how are you compensating them (mentions, other PR?) Start with your local media and see who your local reporters might recommend. Sometimes it just takes one referral to open a world of help.
You may also want to add subject matter experts to the mix (beyond reporters): relationship coaches, organization or professional counselors, shrinks. That way, you get more original content than recycling what’s already been written or broadcast.

You guys rock!  Thank for your input.  You definitely gave me some great ideas.

To give you some background, this book is intended for the lay audience and directed broadly across all relationships.  The structure of the book is going to be similar to a “Chicken Soup for the Soul” approach but much more condensed.  We really want to drive home what helps both strengthen relationships as well as repair them when they are broken. 

I love the idea of guest posting and am definitely going to give that a try.  Our results from HARO have been very disappointing and now I see it may just be how I posted the query. 

To answer your other question, the authors will not be paid but we will be promoting them across our social media platforms in addition to introducing them to a few other incentives we will be rolling out to our panel of “Experts”.

Thanks again!  Love these insights!

@gregorybuford People are more likely to respond to something concrete: “I’m looking for guest authors to contribute an article of up to 500 words on one of these 10 relationship topics…The deadline for submission is June 1, 2012. Every article that is accepted will be published with your 100 word bio and your bio will also appear on the Web site promoting the book.” When you read a blog post or comment that seems to ring true to your theme, you have something specific to send along with your request.

good move Glen @glengorham have you tried scoop.it for curating information?what is your exposure reach? @gregorybuford