Often times at first glance a board looks straight and the fact that it is actually bowed or has some warping isn’t always obvious. So the trick to knowing for sure, is to hold the board up towards your face, with the other end on the ground, and look at it at a downward angle (as shown in the below photo). This method will allow you to see if it is bowing at all.
Let’s be clear about one thing: No workshop is perfect for everyone. If there were, I could simply give you a precise plan to follow with clear dimensions. Every person who comes to the hobby, avocation, or profession of woodworking has his own particular collection of tools and his own peculiar work style, skills, and desires for the kind of woodworking he wants to do that gives him a unique approach as to how he will lay out a shop: where the tools should go, where lumber and supplies are stored, and how much bench area he needs.