The Presentation Zen Sketchbook is the first sketchbook I actually filled, and re-ordered. It’s great because:
Some pages have a 2×4 grid of boxes, which is perfect for multi-step user flows or planning presentations, but
Some pages are blank, allowing you do to freeform sketching, but
Most of the “blank” pages actually have small images and phrases, which avoids the mental block of staring at a blank page, and
It’s not too big or too small
Highly recommended if you’re not happy with what you have.