Were doing the Glory next month and Magic in November 2011.
I would agree that if it is your first cruise you may want to do a shorter one.
Magic is new..well about 6 months new when you are sailing...so it should be in great shape for you.
Can't speak to the condition of the Glory yet. Look around at several reviews on the ship before coming to any decision. Visit the Carnival forums at Welcome to Funville | Carnival?s Online Cruise Community | Carnival Cruise Lines
and read what others say about the Glory.