WIFI Guest is great and popular topic, since all the companies want to provide WIFI guest access, but nobody wants to manage it.
It's really amazing to see, that a lot of companies have Guest access in place, but it is becoming a nightmare when there is an actual need to connect.
FISid approach is to bind the WIFI Captive portal to the strong authentication server. A Display Card is then provided, on which the SSID and the user name are pre-printed and the password is a OTP.
When an external people is asking at the desk for WIFI access, a simple exchange of an ID with a Display Card will allow the guest to have access and will allow you to have a full treacability.
In this configuration, your WIFI is very secure and does not need any management at all.