Just got home late last night. We brought tank tops, shorts, etc. and luckily our heavy fleece jackets which I threw in at the last minute. Most days we wore our jeans (not shorts), sweatshirts, t-shirts (not tanks) and socks with runners (not flip flops). A couple times, I'd wished I'd brought my lighter Helly Hansen jacket.
In addition to these layers, we wore our heavy fleece jackets at night! It was not warm (for reference, we live in BC Canada) and it was about the same temp up here while we were in DL. A couple days last week were warm enough for shorts, tanks, etc during the day, but mornings and evenings were cool.
For the kids: Our kids all wore sweatshirts and fleece jackets layered at night and we brought a warm fleece blanket for the 3 and 4 yolds in strollers. So, if I were you I'd bring the works and also be prepared for a little bit of rain, which wasn't bad with our windbreaker type jackets on.
Happy Planning and feel free to ask any more questions!