Criminal charges? Trespassing... what else
As citizens its OUR house they entered.All americans should have access to it.
Just as there are certain hours you can enter places (public parks, city hall, an armory etc) there would be certain hours for visitors to enter the WH (they have set tour hours).
But aside from walking in (and being allowed by the Secret Service) without the invitation, trespassing seems the only real charge. Someone mentioned to me lying to a Federal Officer. Possible I guess.