My father just passed away (last weekend) at 87 - he suffered from Alzheimer's as well.

He was my dad, but as the disease progressed he got testier and more difficult. One of our last trips together, I attended his internment camp reunion with him. He refused to stay in the hotel because for some reason he thought the manager was prejudice and didn't like Japanese people. Like a kid he refused to even set foot in the room and sulked outside until we got other rooms (which weren't as nice but for some reason placated him). I had to show him "Dad, look around, everyone in the hotel this weekend is Japanese! Not just you!".

Enjoy the tame moments - they do become precious few.