I also have the Hidden Mickeys book for
Disneyland, but the thing is, as the book tells you, the ones they list are only the 'confirmed' ones or the obvious ones. There are plenty of other ones that the Cast Members won't admit to or shapes that look just enough like Mickey to make you think it is a hidden one, but is slightly askew so you are not sure! We never look for them outright, but if we find them, we always feel as though we have accomplished something, and by the time we leave, we think we see Hidden Mickeys in everything!!! We could not find a single Hidden Mickey in our Grand Californian hotel room, or in the carpets, but when we stayed at Paradise Pier, I think we saw some in the patterns.
When I was just at Disneyland right before Christmas, I spotted a very obvious one, although it was seasonal so it will not be there year round) in the Haunted Mansion Holiday. When you go past the dining hall/banquet scene where all the ghosts usually dance, but which is currently adorned in Nightmare Before Christmas Holiday decor, look on the floor, over to the far upper right corner of the floor. There is what appears to be 'snow,' I guess, but it is a VERY obvious Hidden Mickey. Honestly, it looks like a white Mickey-shaped fuzzy bath rug!