We used SeaWorld's complimentary Land Rover transportation when we went to Discovery Cove. So when they dropped us off back at SeaWorld, we spent the rest of the day there. (Got back from DC about 4:30) Depending on what time SeaWorld is open till (7:00 in our case), you will only be able to see a few things before close, which was fine with us. We rode the Atlantis ride, saw the Shamu show (daughter's highlight), fed the seals, saw the penquins.
Just show the person at the turnstile your badge from DC, you get right in. You get to bypass the ticket lines.
If you have any other DC or SW questions, let me know.