It was built back in the 80's by a Japanese company. I think they originally named it the Emerald hotel, then later changed it to Pan Pacific.
Disney bought it in the 90's but didn't really do anything significant with it until DCA. Then, of course, they transformed it into the hotel you know today.
What I like most about it is that it still retains some of it's character from the original "Japanese" version... like the Sushi restaurant and the fact that it has a 13th floor (I guess Japanese folks don't care about 13)
My favorite dumb joke is to walk into an elevator and if a nice stranger asks "what floor" I like to reply "13 please". I have to remember not to do that there ;-)