I am not sure about the Disneyland hotel, but at A-Kon there
was a bagage check.  You went to a special desk and the clerk
would watch your bagage for you.  

Basically it was for people that had checked out of their
rooms, but were still attending the last day of the show; thus no
where to put their luggage since they wanted to stay tell the end
of the show!

Since I was working at a table I was lucky enough to be able to store
my stuff there.  Afterwards though since my flight was another 5 hours
later I had the same problem.  I went to the same clerk and explained
to him that I was wondering if there was a bagage check.  He said there
was, and gave me some tags for my bagage (behind him was a huge pile of 
bagage though in the lobby).  I then went on to explain to him that
he needed to be very carefull with the contents of this one bag, as
it's contents were worth about $35,000 and I (implied) that I didn't
want it put in that pile.  

The gentleman understood and took my bags to a room where he had to
unlock it, and them placed them in aforementioned locked room.  Afterwards
when I came to pick them up I gave the man $5 and he was more than happy.
The contents were all undamaged and obviously taken care of.

In short, I guess if you are worried about leaving your cels unguarded, ask
the hotel if they have some kind of secure storage area.  While it may cost
a few bucks it's worth the peace of mind.

Brian