Leave enough room for door openings (entry and shower) and trim. Keep in mind existing features, such as mirrors, electrical switches and outlets. For standard building code compliance, allow at least 18 inches from the cabinet edge to the center of the toilet.
We recommend sealing marble and granite countertops twice annually. The reality is you can never over-seal your stone. Frequent sealing provides constant protection against most oil-based stains and the same is true for water-based stains such as tea, wine or coffee.