Found linked elsewhere on the interwebs, this is a nice article on using grids for layout. It's quite easy to understand, with examples.
Designing Layouts in RPGs — The Explorers Company
Grab your sword. In this Design Delve, we're going to learn the arcane art of designing amazing layouts for tabletop roleplaying games using the infamous grid system. Layout design is game design. Find out how to layout your next project.
www.theexplorersco.com