Use some graph paper, draw your outlined options for a work space and place items (bench, saw, etc) you intend to fit into the shop within that virtual space. This may (or not) negate some of your options regardless of your preference. Also, factor in door's, windows (near benching for example) and ventilation as this will reduce wall space fairly quickly and again determine options. You also need to work out head space based on the type of roof structure you have which would lead into the only other advice I can offer which is to factor in storage. Like most workshops, it is often an afterthought and will always be a regret in my experience.