I've been to SeaWorld twice and it's "sister" park Discovery Cove once.
SeaWorld is fun. It's essentially an aquatic themed zoo and amusement park. I love the Atlantis boat ride (it's like an ancient and somewhat spooky though funny Splash Mountain), and the Krakken roller coaster. I also love the Budweiser Clydesdale horses who live there. They are huge and beautiful. If you don't know what a Clydesdale is (because many people don't) they are the horses from the Budweiser commercials and Bell's horse Philippe in Beauty and the Beast.
There are also tons of cool shows but I've never really been able to see any of them other than the Cirque de Soleil one because all the shows have only a few starting times and the arenas fill up very quickly. If the time is approaching or you've just plain momentarily forgotten then you are out of luck. I now think it's best to plan to see those ahead of time. Keep in mind that if you arrive at a time when a killer whale has just been born the famous whale show will be nonexistent. You'll simply get to see the mommy and baby swim around together and footage of the baby's birth, all of which was very insightful and cool to me at first but then got boring pretty quick.
Honestly, although I've made two visits to SeaWorld I only remember eating there once. It was one of those cafeteria style restaurants and the food was alright, not memorable and not bad. The packages with Discovery Cove or at least the one we had came with food in the sense that you just grab a tray and walk right over. It was kind of like the barbecue buffet that Disney serves when you first get to
Castaway Cay during one of the cruises. If memory serves, you could also get snacks whenever you wanted. Discovery Cove definitely had better food, a nicer atmosphere, especially since you felt like everything was taken care of.
You can do SeaWorld in a day or less depending on what you want to see. It's no where near as packed full of attractions as the Disney parks are so it's pretty easy and relaxing to explore. It's nice. It has aquariums with a bevy of exhibits from penguins to manta rays to dolphins that you can pet and feed. Feeding SeaWorld's dolphins is very fun but still kind of pales in comparison if you've already swam with the dolphins over at Discovery Cove.