The main criteria to consider are the natural features of the building lot. For example, if your plans include a walk out basement, a lot with a fair amount of slopes and hills will be best suited for your plans. Take into consideration the movement of the sun. Will sunlight be coming through your windows directly or at a sharp angle? Window placement can directly affect the natural lighting of your home and be used for heating during winter months. If you would like your luxury custom home to include large windows but also allow your privacy, you might consider a lot with trees.