Sea World is great, but it's not Disneyland. So, I recommend 2 days at Disneyland (ask how Fast Passes work with little kids), 1 day at California Adventure (if you get done earlier you can always walk over to Disneyland later because it's open later), and 1 day at SeaWorld (map out ahead of time which shows to go to and at what time because it helps to not waste time or any extra walking). If you have the time, I would also recommend a rest day in between to sleep in and go to the beach, or something else relaxing. The City Pass is great, but it was too much for me to handle with little kids. I needed a rest day. You could price compare the city pass to other prices. The Disney Store has discounted tickets too. I believe that you still have like 14 days to use the passes from the first day you use it, so they don't have to be used in consecutive days, but I would double check on that too.
Your kids are old enough to probably make it without a nap? I would definitely recommend taking a double jogger stroller for your 2 little ones though -- lots of walking and if they need a nap you can find a shadey spot and rest for an hour. You can check them at the gate at the airport, or Disneyland also has them to rent if you'd rather do that. I would also recommend a little cooler with snacks and water to hold you over between meals, etc. Take a squirt bottle if it's during the hot weather time. The bike backpacks that hold water are great too. If you go during school, the lines aren't that bad. The best time to go is in February, in my opinion, because the weather is perfect.
Have fun planning your vacation. Most of all, just have fun, no matter what you end up having time for.