Disneyland has always been, and will always be, my favorite theme park. I've always found it clean, the cast members bright and happy to be there,and helpful.
I think that Six Flaggs, and Great America (in Nor Cal at least) are greatly overrated and over priced. Six Flaggs Marine World has gone downhill since SF took over. The animals aren't being kept in the best of conditions, and the rides don't look particularly safe. I've never seen ANY of them closed for refurbishment, safety checks, etc. As for customer service, it's practically non-existent. We waited in line last month for an HOUR to see a 3D dinosaur adventure. (all signs and displays had my son psyched to see this) When we got in to the theatre, we sat through a 2 minute Sci-Fi cartoon that was a rip-off of STarGate. My six year old was not pleased. I then waited in line at customer service to suggest to management that perhaps they should change the sign, or make announcements to advise that it was NOT a dinosaur movie, and their suggestion was that i write a letter. The "manager"was too lazy to even apologize or write down my complaint, except to say that they'd changed the feature over a year ago! I guess we should have known this via ESP. Glad our last trip was paid for by my husbands employer and not us.
Great America is a dump. When I was last there 15 years ago, it was overrun with punk teenagers and gang bangers, and from what I've heard, it still hasn't regained the right to call itself a "family" park.
Sea World, on the other hand, was a pleasant surprise! We were there in June (after our first trip to Dland this year) and really enjoyed ourselves. The ride operators and park personnel all had that "Disney" quality although the parks are not related. They were all friendly, helpful, and knew a lot about their jobs and the park itself. It was extremely clean and well cared for, the animals were kept in terrific conditions (as good as they could be for animals in captivitiy), and the food concessions offered selections that would rival the River Belle Terrace and Blue Bayou.
I hadn't been there since 1983, although we're at Disneyland every two years, but I'd like to go again on our next trip down south.
As for California Adventure...I like the Grizzly River Run, the Redwood Rec are, Soarin',and Hollywood pictures backlot. The rest of it - no big deal at all. I was very disappointed - I think they should have taken more time to plan it, spent more money, and make it more "Disney", put the imagineers on it instead whoever they hired to design it. Not enough time, energy, or talent went into it. And in most areas of that park, the cast members don't have that sparkle and interest that DL's cast members have. We only spent 3 hours there last week, and 1 day in June out of four, and stayed with the rest of the crowds in the Magic Kingdom.