The original poster did not mention how old his kids were. That can play a huge factor in what kind of dog you get. My pup is wonderful with kids of all ages but he is best with little ones (under 3) and slightly older ones (10 and above).
The 6 to 8 year olds are too unpredictable and for some reason he wants to herd them the most. It has been more work for me with that age group. Not with the dog as much as with the kids. If you know you can spend the time and energy go for it.
I would also lend my voice to rescue. BEing in Frederick you have a wide variety of areas that you could do face to face with the dogs fairly easily. You can look in Md, Va, C, West VA, Pa and even Del is not too far for a family trip.
Liz