Perhaps I'm mistaken but I thought that was the rule at the Tropicana (and many other Vegas hotels.) Certainly no one will stop you from checking out on Saturday provided you've paid for the extra day. For the past two Conventions I've stayed at the Tropicana through Thursday night then checked out on Friday and stayed at the lovely San Remo for Friday night so I could head for home Saturday afternoon. The drive back to LA is a lot more pleasant on Saturday than Sunday.