OK, now we can help you narrow this down.
As clkelley already pointed out, if your DH reserved a Full Hook Up site, then you will be limited to the 1600-1900 loops. These are the only Full Hook Up loops in the Fort, so you will be assigned to one of those four. If you are not sure about this, you should double check, as if the reservation is for a different type of site, you will not be assigned to any of these loops.
But, if it is definitely a Full Hook Up reservation, then here's my $.02:
If being close to a comfort station is important to you, then I would recommend the 1600 loop. There is a comfort station between 1600 and 1500 and also one between 1600 and 1800, so you have the best chance of being close to a comfort station on the 1600 loop.
As far as room to run around, both the 1600 and 1800 loops border a canal and pet walk area. You may not want to be close to the canal if your kids are small, and you are concerned about them getting in the water, but, otherwise, there is plenty of room to run around along the canal. This is also a good place to wet a line (fishing term). Also, the 1600 loop has the easiest access to the Meadow Recreation area, where there is a playground, tennis courts, shuffle board courts, and, of course, the Meadow Swimming Pool.
So, for you, I would say request 1600, and then either 1700 or 1800 as your second and third choices, and 1900 as your last choice.
You will have fun on any of these loops, so don't worry too much about it. They are all right next to each other, so while the 1600 loop is closer to the Meadow area, the others aren't that much further.
Happy Camping!
TCD