Reporting SEO activity to clients

I'm currently reviewing our overall SEO strategy and offerings and one thing I've been concerned about for a while is our reporting, As an agency we work on a number of different clients and we tend to report on a quarterly basis but the reports we use are cumbersome and inflexible. I'm looking to practice what I preach by conducting a review with the users of our reports, but in the meantime I was wondering if anyone was willing to share any tried and tested successes.

My main concerns are that the reports can be a little dry, and don't tend to provide a client with an accurate enough picture of what we've been up to and what result our activities have had. Have you found this and if so what have you done to resolve it?

Thanks in advance