My family has been to WDW many times and we went to DL in 2001. Don't bother going to DL for the Magic Kingdom. The one in WDW is better by far - there are few things they have in DL that aren't present in WDW, like the Matterhorn, but I wouldn't make a trip out there just for that. As for California Adventure, it was great, but again it has only a handful of things you can't find in WDW. You can find something comparable or exactly the same at one of the parks in Florida. They both have tower of terror, a river rapid ride, It's Tough to Be a Bug, a power launch roller coaster, etc. The things CA has that WDW doesn't aren't worth the effort. They have a great hangglider simulator ride called Soarin' over California, but I wouldn't trade it for Body Wars, Star Tours, and Mission Space.
If you will be there for a while and want to go to the San Diego Zoo and sight see in LA, that's great. The La Brea tar pits are great, you can shop in Beverly Hills, see Hollywood, there is a ton of stuff to do out there. If you drive from Anaheim to San Diego, take the Pacific Coast Highway and you can see some great scenery along the way. But, don't go for Disney. You'll have a much better Disney experience in WDW. The park as a whole is so much better. Better hotels, better location, in my opinion better food AND better service, and many more options. In DL, you just kind of have to take what is available. Being from the Midwest, I was looking forward to it because I'd never been to California before, but I was disappointed because there is really no "SoCal" feel to the Disney area. The highlight of the trip for me was finally seeing the Pacific ocean.
The weather is pretty much the same. California doesn't get quite as hot and it doesn't rain as much, but for the most part both places are comfortable year round. The prices are comparable. Both admissions are around the same amount, and souveniers and food are standard whichever one you choose. However, you don't have a choice of price ranges in hotels in DL if you want to stay on property. You have expensive and more expensive. There are no value or moderate resorts.
For me, I'd choose WDW every time, just because of the variety. DL doesn't have anything like Epcot, which is my favorite, they only have 3 hotel options, and only a handful of restaurants, whereas WDW has something to please any taste in any price range. If I go back to LA, I will probably not go to DL, because when we got home we felt like we didn't see enough outside the parks.