There TONS of hikes to pick from!! I’m assuming you would be heading for the mountains, possibly Shenandoah Nat’l Park since you mentioned summits or waterfalls.
One that comes to mind is called Blackrock Summit. It is a very easy hike–about a one mile trail, but the summit has a HUGE pile of giant boulders that used to be a seabed. It is really cool and there is a great view. Kids (and adults) enjoy climbing around the rocks at the top. https://www.nps.gov/shen/blackrock-summit.htm
If you want a waterfall, Dark Hollow Falls might be a good one. It’s tougher because you walk down to get to the waterfall but then have to hike back up–but definitely doable even for a beginner. That one is 1.7 miles total. The falls are impressive!! http://www.gowaterfalling.com/waterfalls/darkhollow.shtml
Hope this helps to get you started. If you need more help, let me know!! -Kim