No doubt, Disneyland Resort is the Happiest Place on Earth. This is the park that Walt Built. However, this park is tiny compared to the Magic Kingdom. You know all those stores on Main Street at the Magic Kingdom? Try taking out four of those stores and you got the DL version. It is amazing how Disney is able to work just as many attractions in DL as there is in MK, but at a fraction of the size.
I believe Disney had no idea that his theme park was going to be such a cultural phenomenom. If he knew that, it would have been built somewhere bigger.
Good? Better? It depends on what you consider the benchmark of good and bad. DLR has the historic rides. You are experiencing the original Tiki Room, the Jungle Cruise, the Mad Tea Party, The Matterhorn. Some of these rides are over 50 years old. However, both parks are on the smaller size. Because of this, there are not as many restaurants, hotels, and shopping opportunities. WDW does it well, but uses size and theming to really get you into their world. At DL, you know that you are still in CA.
As for your question, I would say 3 to 4 days is enough for Disneyland Resort. The other interesting dynamic is that the other theme parks actually play nice and work with each other to offer special deals. I would be prepared to go to another theme park too. I would suggest USH because, it is the actual Universal Studios!
Tokyo > Anaheim > Orlando > Paris
Better maintenance, food quality and the overall convenience of a walkable resort give Disneyland the edge over WDW, for me.
I have found that people who are used to DL do not necessarily like WDW.
What makes DL better maintained and better food? I did not see anything like that when I was there. That's not saying that DL was shabby and had crappy food. I just didn't find it any difference in maintenance and food quality. I would argue WDW has a bit of an edge just because quantity. It is easier to get around, I will give you that.
I have only stayed at the Grand Californian and Paradise Pier. I have heard good things about Disneyland Hotel, but it appears to be the furthest from the action.
The Grand Californian is, of course, spectacular. Its right in the middle of the action and has that Disney Charm. Its a bit pricey though. Still, they have their own gate into DCA.
Paradise Pier is very nice, but it probably will remind you more of a Double Tree Hotel. A nice business hotel, but lacking a bit of the Disney magic. Still, the rooms were nice, the view of the park beautiful, and a pretty good character breakfast. My family really liked this one.
Regarding hotels, the only really worth is Gran California. The other 2 are more far away from the parks than the many smaller hotels, with better cost benefits, you can find outside the resort.
I jogged around the whole resort area every morning and did not see any local hotels/motels that I would have preferred over Paradise Pier. And while some of them were as close, I did not see any that were substantially closer. Not enough to sway my opinion, anyway.
It sounds like you are going on a once in a lifetime trip - so make sure the place you are spending your downtime is more than just a cheap place to sleep and shower. It should be part of the experience, IMHO.
Walt Disney World
Tokyo Disney Resort