The only reason I'd reserve DCA for the morning is to do Radiators, Guardians, and Spiderman without a long wait. All of the other attractions in the park don't really get a long line. Radiators, Guardians, and Toy Story begin to get long waits after about an hour or so into park operation if the park opens at 8. Personally, I'd do 2 reservations for DL and 2 for DCA. If you feel like during your trip you want to change that though, reservations are pretty easy to come by for ticket holders currently. Esp during the week, you can get reservations the day of but it all depends on what exact time of the year you're going.
DL kinda gets long waits right off the bat. Space and Indy are the two that most people head to at rope drop. However, if you're going early next year like late January or early Feb then wait times shouldn't be a big problem, esp on a Monday, Tuesday, and Wednesday. If you're going at the end of winter break then it will be completely packed.
@PiratesMansion also brings up a good point about getter chances for Rise boarding groups with reservations for DL.
For things to do on the weekends... it kinda depends on where you're staying, how far you're willing to go, and if you have kids with you. There's Huntington beach that's about 20-25 mins away from DL and the Cube Discovery Center in Anaheim that's 5 mins away from the resort. Downtown LA, during a good time of day, is only about 25 mins away and there's a bunch of stuff to do there. There's the Santa Ana Zoo too.
It sounds like a fun trip and I hope you guys have fun!