OP didn't see your question sooner. Did you go this week? How was it?
Easter week is usually busy and they stay open till 10 but really don't have a lot of shows in the evening. They add a One Ocean and Clyde and Seamore show, but they don't do the shows that they do during summer months or have fireworks usually.
A lot of people leave after 5 or 6 to go to eat or to Disney for fireworks. The rides are open to closing but they are about the only thing to do besides shop and eat after 7 or so unless you go to the 8:30 One Ocean Show. Usually Kracken is one my kids ride over and over during the last show toward the end of the night.
We like going to Pacific Point and watch the sea lions and harbor seals bed down for the night.
At SW the lights are dim more like streetlights in a small town so it feels like you are out taking a stroll on the back side of the park after most of the people have left . We used to close the park down a lot when our son was going to UCF. We would meet him for dinner(mostly to give him more money and make sure he was eating<g>) and then just talk while we walked from sea lions to dolphins viewing etc.