I personally love SeaWorld and I am hoping for a chance to work there as an intern this summer. While none of my recent trips could ever compare to the trips I used to take as a little kid to the old park in Ohio (they used to select a 4-5 year old from the audience to sit on Shamu during the show, being chosen was the highlight of my life, lol), I still enjoy the parks. Last February I took some younger teenage siblings and cousins to the parks for a day during our Disney trip and we also did Discovery Cove. As it turned out, SW was our first day with the free tickets from DC. I think the trick to enjoying the park is to NOT compare it with Disney. They are pretty different concepts and grouping them together makes it hard to compare. If you or your kids really love animals or Animal Kingdom, you will probably enjoy SW. If you are focused mainly on rides it isn't as likely to entertain you. One day is not enough to view all of the exhibits, rides, and shows but with some planning ahead of time as far as what shows you are going to and setting some priorities for exhibits and rides you will still have a great time.
Our second day in the park was spent at DC. That was a great experience. They are pretty good about making sure that you are treated like a guest and they do a good job of "pampering" you while you are there. I know the teens in our group loved having someone cleaning up after them or telling them to sit down when they tried to take their trays and garbage up. The entire place is beautiful and because they limit the number of reservations it is a nice, relaxing day in the middle of the usually hectic Disney trip. If I could afford it, I would schedule a DC day in the middle of all my WDW trips or at least the non-dolphin portion. The dolphin dip was great to but it was very staged for pictures and videos as opposed to mainly the dolphins. That can be great too and I loved it but I have heard a lot of the people who did other more interactive programs complain.
Four years ago I also did the SeaWorld Adventure Camps which was so much fun. I went with a cousin to the Career Camp in San Diego. We had a blast but one thing to keep in mind is that there isn't a lot of interaction with dolphins or killer whales though. We did get to go behind the scenes and/or pet a Beluga Whale, manatee, and even got to go inside an pet the penguins at there encounter. It really seemed to be geared towards those kids who wanted to become animal trainers or caretakers (all 40 high school kids except me and my cousin wanted to be a SeaWorld animal trainer). You do a lot of grunt work and preparing food for the animals and shadow various caretakers. I would def. recommend it though if your kids are at all into marine animals since it was a pretty unique summer camp!