Wi-Fi Security implementation help..

Hi I am very new to Wi-Fi stuff. Recently I was asked to implement Wi-Fi in our premise. hardware that i used 2 nortel WSS 2360 and 17 AP 2330 powered by POE adapter.

I have configured this switch using quickstart and I have only implemented clear SSID, which is no way secure. To work on the security I have to implement either 802.11i, WEP, or WPA type of encryption. However, if i implement this either users have to enter their names in AAA database or use PSK.
Which is more suitable kind of encryption for me to use so that i dont have to run to every users educating them about PSK or user id or password. On the other hand I want secure Wi-Fi.

Thanks.