Depends on what you are going to be doing on top of the bench. I build a lot of models and so I almost always have 4 glass working surfaces on the bench - these are all ~ 20"x30" work areas. They are also on various underlayments such as carpet padding.
Lighting is critical. I have several LED shop lights.
The entire back foot of my bench are parts bins. Most of the rest of the shelving are more parts bins and trays for specific materials and parts.
Commonly used tools are in several racks (3-7) that resemble oversized test tube racks - 2 hold just hemostats (10-15); 1 holds nothing but tweezers, etc. Another space hold 5-8 different scalpels........
Something else that I've found highly useful is to pause now and again while building (pausing for photography) at various stages and to clean up, clear the work space, and put all the tools away so that you can actually quickly find everything when moving to the next stage where you may need a slightly different selection of tools. Putting all those you do not need declutters the work space.
