Discovery Cove is a very relaxing day. Nothing to plan, just go. Included with the food is beer and alcoholic slushies. If you want to feed the birds, do that early. Once they are full, like later in the day, they are not as friendly. Since you can basically snack all day, don't plan on a big dinner that night. If you feel like visiting a park, SW is across the street, if you want to go there after DC.
Aquadica is a fun waterpark. You may take all day, or leave in the afternoon. The food is better in the restaurant that is not a buffet. The meal plan there is not that good. If your boys like slides, there are several. My teen DS and DD11 both like the racing ones.
SW is a fun park too, it's all about rides and shows. To see all the shows at a lazy pace, take 2 days there. If the park is open late, you may want to buy the dining plan. There one restaurant even serves breakfast. Lines are good for snacks and drinks too. Water bottles are part of the plan, you can get them at any restaurant by going through the line. If you ride the Atlantiis ride, and sit near the front or sit in the splash zones of the orca show, you will get wet, most likely soaked. You may want to keep a change of clothes or wear clothes and shoes you don't mind being wet in.
If you are driving to SW and Aquadica, call DC and add a parking pass. The pass is around $25, and can be added to your DC package. If you want to visit the other parks before your DC day, just go to DC and pick up the pass before going to the other parks. Pass is good for 14 days from date of issue. Otherwise, parking at each of the parks is about $15/day.
Have a great time! We love Orlando in the August heat. If you are hot, find a shaded spot in Aquadica or rent a cabana. In DC, there are many shaded areas, and you can always sit in the restaurant area, there are umbrella tables and chairs there. In SW, find a store and other buildings that have AC. It will be hot.