I think I picked one of the hottest days imaginable (heat index was around 100 degrees), but was such a cool experience to be out on the National Mall in DC for this amount of hours. I started around 4:30 AM (with much to my surprise many other runners were out there) and spent the remainder of the doing laps on the mall. I had a number of friends stop in and run or bike along side of me, and I was able to park my car on the mall to have my own crew station where I could refill water, grab food, change clothes, etc. The really crushed me, but I kept it together and ended in good spirits around midnight. I'm excited to see anyone else give this a try as I highly recommend it - it's repetative for sure, but its a really amazing experience in its own way :)