To hold paramount the safety of the people getting in the elevator is first and foremost. Therefore, if the elevator can hold only 1000 pounds, the elevator has to be built with small dimensions since most people do not look at the capacity; they squeeze until there is no more space left and you never know the weight of different individuals, if they have luggage with them, etc. After taking into account the dimensions of the elevator, we have to take into consideration the performance of this elevator during peak hours. How many floors in the building? Are there multiple elevators? How long does it take to take to get from the bottom to top floor. What will be the wait times of people waiting for the elevator? You wouldn't want people getting frustrated with waiting with the elevator so depending on how many floors and how much traffic is coming through, you might consider having multiple elevators. What is the budget? Does the budget allow us to have multiple elevators? If so, is it worth it. We must also look at the performance of the elevator. When I click a floor, how long does it take for the elevator to close. If I click the open or close button on the elevator, do they work? How strong are the sensors on the elevator if a person tries to rush to get on the elevator when it is closing. After designing and building the elevator, do periodic checks to make sure the performance is ideal and has not regressed.