I have terrible ankles that are partially unstable. With this in mind, it will be to my detriment to climb stairs multiple times a day. The elevator will be enough to carry people, and bring in furniture such as a full size bed. Anything larger will have to use the stairs. The elevator will service all floors, and there will only be a need for one.
On another note, the elevator will require a telephone line. The telephone jack will hopefully connect to a POTS to Cellular gateway. This will have to be 4G LTE as GSM 3G is being phased out in the United States. If a gateway can not be acquired, then an ATA plugged into the telephony server built into the network server will be used. In that regards, a dedicated extension with its own telephone number will be used.