Another thing you need to think about is the refrigerator capacity. The primary factor that you should be considering is the number of bottles that you need to refrigerate at one time.
Keep in mind that the 6 - 25 bottle capacity is considered as "small." The "medium" capacity is 26 - 37 bottles. The "large" capacity can hold anywhere from 38 - 66 bottles. There are refrigerators that can hold more than 66 bottles. However, these are mostly designed for commercial use.
Other minor factors that can help optimize the refrigerator space is the bottle type, shelving material, bottle configuration, and zone capacities.