I have to disagree with the majority here. Disneyland is probably the single best park Disney has in America. It is not a day theme park. I usually do 5 days between GCA and Disneyland, obviously you can spend more time at WDW because there are more parks, but as someone who's been to both more than a couple times, MK is always a let down to me because it feels like a shell of Disneyland. There are things it does better and I love WDW, but Disneyland packs so much in, I love it.
To name them,
Indiana Jones (I never understood how WDW didn't grab this),
The nemo subs ( I haven't ridden them but oh man I want to),
Matterhorn (for me, 2nd only to EE),
Roger Rabbit (Cool Dark Ride),
Toad's Wild Ride (You're probably familiar with it).
Pirates, both SMs, Buzz Lightyear, Thundermountain and probably some others are different. The edge, imo, goes to buzz and pirates at DLR fairly distinctly, Space Mountain I like a lot more at DLR, Thunder and Splash at MK though.
GCA is really a day park, there are enough attractions that you can't honestly do them in a half day or anything. If you go, catch the live show, and do things there during the busy times at Disneyland. Between the two you hardly ever wait and line and they are literally 2 minutes apart from each other. When I'm at WDW I always wish the parks were that close because park hopping can be a task. California Screamin' is great, and the River Rapids ride is so good, makes Kali look just awful.
This may not be a consideration for you but, at Disneyland you can stay offsite and still walk to the parks, so you can save a lot of money that way, at WDW this usually entails renting a car and paying for parking or relying on infrequent shuttles, which means scheduling your time around them. Basically, staying offsite costs a lot in time or money at WDW, not the case in California.
As for attractions around Disney, nothing interests me outside of either parks except for Nasa, so it doesn't really factor in for me. Having said that, I love the west coast of Florida and in California, San Diego is beautiful as are the attractions there. These are more like full day trips that require some hours of travel though, which I don't mind, but isn't for everyone.
I'm not saying DLR is better than WDW or vice versa, I am just of the belief that they are both great and it's an absolute shame if you're a Disney fan and don't go to DLR, it's at least as good of a time, but yes you will probably only spend 4 - 5 days there (I could spend 7 easily and be happy but I could also spend a disportionate amount of time in WDW

). You could whirlwind everything in 3 days I'm sure, but I don't think if you're on these boards thats your intention.