Hotspot idle timeout or the like

Using a radius server and 750’s as NAS devices in various locations for authentication. Having an issue with users that have ipods/ipads or put their PC’s to sleep. Anytime they do this they have to login again which becomes annoying. I want to allow a login session to stay active for up to 3 days before a particular client is requested for access credentials again. What is the best way to accomplish this?
Looking at my hotspot settings, it appears I should modify user profiles-general-session/idle/keepalive timeout settings. However, under Hotspot server there is a keepalive and idle timeout options too. Or should I just enable cookies and set the time limit there?

Suggestions?

Thank-you

The user profile keepalive/idle values are applied to users logged in under that profile. The Hotspot server keepalive/idle values are applied to unauthenticated users (includes MAC bypassed users under IP bindings).

Also using cookies would be a good idea.