This is where I'm going to struggle I bet. I've got limited time as I have a wedding I'll be rushing back from. Although maybe I could do this Horseshoe Meadows. Does it get filled up fast?
At HM, the place to stay is the camping area on the south side of the area (don't take the right turn coming in). HM is wide open and flat. Except for the foxtail pines and a few bushes/logs, it is just flat sandy ground. If you're going there to spend the night, you can always find a spot to throw down your pad and bag. You can even park and sleep in your car if that works for you. Since it is officially a one-night-only camping area, it never fills up.
Running shoes: is the summer trail too rough for them? I'm on the fence between using ventilated, soft, light running shoes vs. GTX, stiff-soled, heavy-ish hiking shoes.
Last summer I used these to go up the Mountaineers Route and down the Main Trail. By the end of the day, I had one blister just rear of my big toe. I'd use them again for the trip.
http://www.zappos.com/p/new-balance-leadville-red-black/product/8646277/color/1413