Chafing hurts, the first aid stations have Vaseline if you need it. I didn't know this, but my wife asked and got some and it helped her. I had pre-greased, but could have used some re-greasing at 20 miles or so.
Also, There were some cold people at the starting line. I think they thought the thermal blankets would work better than they did. I wore some pajama bottoms, and a cotton jacket. Both went into the bag before the race, and when I started running I was fine. I kind of like the cold though.