The best way to plan your Wi-Fi setup is by requesting a free Aerohive Wi-Fi planning demo from us. This great tool will allow you to draw a plan of your space and calculate the amount of units you'll need.
In general, the type of access point you need depends on the place you install it into. The best place to put your AP is the ceiling - this way you get the best coverage even with the models without external antennas (for example, Aerohive AP121). However, if you want to put your device on a wall or hide it in a cupboard, consider a more powerful model.