The Portal supports two skins, the user skin and an admin skin.  The idea is that an admin skin can be more simple etc for easier management where the user skin is the flashy cool looking skin. If you want to have logged in Admin see a different skin, then this option would work, I do not know of a way to switch skins just when a user logs in. 

What you can do is have pages only users can view after login and give the individual pages the different skin...  You can even configure the portal to automatically redirect them to that page on login.  If you wanted to test this (as I do not know it will work) you could try creating your other User Page with the skin you want, set its visibility to register users, then take your home page and set its visibility to unauthenticated user only, then set the admin to send users to the User page on login.  This would give the appearance of having the skin switch.  I recommend testing on a disposable site first incase it backfires... 

NOTE: Admin Skins can be select in Site Settings

NOTE: Page Settings allow you to change the Page Skin

I hope this helps.

Best Regards,

Robert J Collins | Co-Founder & President

Netlogic Corporation

You have to login as Host by default to set skins.  Once logged in as Host, go to Admin > Site Settings.  Under the Appearance section you will see the dropdowns for selecting the skins as shown in the screen below. 

Best Regards,

Robert J Collins | Co-Founder & President

Netlogic Corporation