Give a large suitcase or two to the valet. Easy.
Allegedly, he was staying at the hotel since Sept 28th. That gave him 3 - 4 days to carry stuff up to his room on a casual basis that wouldn't necessarily cause suspicion.
Keeping the cleaning personnel out during that time probably cause him concern, although it's vegas and hanging a 'do no disturb' card on the door for multiple days wouldn't be anything out of the ordinary.