Making a BLE people tracker

I need to make a device that will detect when any of 4 people are inside an office.
I bought an RFIF system from sparkfun which claimed it could reach up to 16 feet but even with large RFID tags Im not getting enough range to track the tags within the room.
I thought maybe there was a way for the four people to carry a small FM clicker that sends out a click every few seconds and that would tell me that they are within range, but even by cutting off the antennae I was unable to shorten the range to be only within the confines of the office space.
My last idea is to do a BLE beacon for each of them and have a central hub that detects them and if possible maybe checks signal strength to be sure that they are within the office... I don't know much about BLE so I don't know if this is feasible...

The idea is to have four lights outside a closed door that tell us how many of the 4 people are within the office so we don't constantly have to knock or peek inside.. The limitation is that it needs to happen without any interaction from the 4 people so they can carry something on their keychain, that detects, but I cant do switches or anything that depends on them remembering to do flip them...

Hope you have some ideas... everything I've found is either too short range or too long range for this...

There is a reason you have two ears and two eyes. It allows you to find direction and distance to objects. With one antenna you always will have issues.

Have you asked the four people if they mind being tracked ?

fxmech:
I need to make a device that will detect when any of 4 people are inside an office.
I bought an RFIF system from sparkfun which claimed it could reach up to 16 feet but even with large RFID tags Im not getting enough range to track the tags within the room.

Hammy has a valid point....it can be rather important to clear this one with them first.
Other than that perhaps use an active type rfid and check the id every now and then.