Well Jack is watching cartoons after the pool, so:
WWC: Trails close depending on weather. No swimming sadly. This could be a good option as it's easy to navigate. There's a main loop with trails that go off of the main loop. They are all worth doing. You can easily for 25-30 miles of unique trail here and dip off to the car whenever really. Also serve food and beer. $5 to park.
Lake Norman State Park is another, @jShort can thrown in his opinion. Not very technical and flows like a poor mans Raystown. Doing all the loops yields 30 miles. One part of the loops is far from the parking lot so you need to bring some food/water.
There is another local trail near me called Rocky River Trail, probably the most unique and has the most technical stuff (not saying much obviously)12 miles of all single track and two steep/stiff climbs. Easy to navigate too as it's mostly one large loop. It's on this dudes Steves property and he's pretty looney. That's the photo of the guy in the shed with the manniquen and fishermans jacket on. This one drains well and usually "opens" first.
I can post some strava loops of all 3, but not really necessary. I'll let you know how the weather is and as long as everything is open, you can do em all!