Disneyland vs Walt Disney World
Having been to both parks relatively recently, I have several opinions on both. Disney World is MUCH larger and easily fills up a week. However, it seems to me that Disney World makes it fun to stand in line. By this I mean that their "queue" area is very elaborate and has lots of stuff to look at, but their rides aren't up to the same quality as those at Disneyland. That is, except for Expedition Everest which was epic.
There is also something to be said for Disneyland being the original. If you go into the Disneyland hotel, there is a section on the first floor of pictures of Disneyland when Walt was alive and it was being built and it is just really cool and historic. If you are used to Disney World, be prepared for Disneyland to be much smaller, in land space as well as buildings, but for it to have more character (haha) and history.