IMO, the best part of KSC is the bus tour. It takes you out to a viewing tower where you can see launching pads from Mercury, Gemini and Apollo missions as well as the shuttle launch pads. You also drive by the vehicle assembly building and learn all kinds of cool info from the in-bus tour video (FYI, the flag on the side of the VAB is bigger than a football field!). You also go to the Saturn Rocket exhibit, where ther are a couple of cool exhibits with movies and of COURSE the full-sized saturn rocket hanging from the ceiling, as well as the capsule and the lunar module, etc. Sometimes you also get to tour the space station center, but we've never had this happen. These are all part of the bus tour, and you could fill your entire three hours with just this. That means you won't get to explore the visitors center exhibits, see the IMAX film, walk thru a shuttle, see the astronaut memorial garden, or go to the Astronaut Hall of Fame (separate admission, I think). We LOVE KSC (DD is going to space camp there in June), but I'm not sure that 3 hours on-site there will give you enough time to see everything. DO NOT skip the bus tour! While you might regret not doing SeaWorld, I don't think you'll regret going to KSC! Can't really *recommend* any of the restaurants in Cocao Beach...everyplace we've been along A1A is pretty run-of-the-mill, food wise. Not bad, just nothing special. There is a Mexican place on the west side of A!A, and a pretty OK restaurant right out on Cocoa Beach Pier, which juts out over the water, that my DD though was "neat, mom"!
BTW, go to southwest airlines and sign up for their rapid rewards program, and print out the membership card. You'll get a 20% discount at Sea World (now you can do both KSC and SeaWorld, just what you need, more decisions, LOL!)