The green and blue one was easy to find: it's a male eastern pondhawk (erythemis simplicicollis)Thanks for your kind words. The park is in southeastern Virginia (First Landing State Park). I was on a trail through the marshy area of the park (GPS coordinates 36°53'15.6005" N 76°0'19.6468" W). Lots of tall grass, just a few trees - it's between the forest and the bay. And thanks for your reply to Raptors - the information you just shared on the behaviors and habits of these subjects will be useful!
The other one is more tricky, esp. because they are difficult to compare at this angle from below, which i normally really like.
My guess is that it could be a female blue dasher (pachydiplax longipennis)
By the way: Did you use some fill flash or macro light on those two?