You did not say what you will be camping in.
I hope it is at least a pop up with A/C. August is very hot humid and wet.
First let me say if you can afford a golf cart, get one. It really makes a big difference and you don't need to worry about what loop you get. As for loop location without a golf cart, it depends on what you want to do most often.
If you are going to be going to and from MK often, If you plan on eating at trails end for your main meals, want to see the fireworks and electric water parade, fish or boat in the lake, then you would be better off in the low 100's loops.
If you want to swim in the pool, go to the campfire program and night movie, rent canoes or other paddle craft for the canals, play tennis, shop at Meadows trading post or pick up your park purchases, then you best bet is 1400 loop.
You have young children, so I would recommend being close to the pools, campfire program and movie. (1400 loop)
I would, if at all possible, at least get a golf cart for when you will be staying at FW and not going to the parks. You can get a discounted rate for a week or more. It really makes a difference in how you can enjoy FW events. Makes it easy to bring a small cooler along for drinks and snacks when you are at the pool, movie, fireworks, or watching the water parade. There are places to park them everywhere. We enjoyed just driving them around the campground looking at all the camping rigs. They have tops and windshields so you can get out of the sun and rain and best of all you cut way down on your walking and waiting for busses.
I just wish they were not so expensive. I can remember when they were only $20 a day.
Wife wants to stay in hotel so I need to make this as easy as possible so this isnt our last Camping trip to FW.
I just reread your post.
Get the golf cart.
and if you don't have A/C, stay in a cabin or you will never see FW again.