I ran the Ragnar Northwest Passage in 2007 and I had such a blast! I was nervous going in because I didn't train enough I felt, but we all did great!
Only real comment I can think of is that don't expect any real good sleep during your down time, we slept on wrestling mats in a high school gym for 2 hours...not real restful!
One thing I am REALLY proud of is that on my first leg, I had this 18 year old guy just fly by me and I tried hard to keep him in my sights at least. During the second leg, I didn't see him at all. On the third leg, which was my longest, hilliest leg, I realized that I was about to pass him on this huge hill...ME!!...I did, and I beat him and that felt awesome. It was just a quiet competition I kept to myself, everyone involved were so supportive, kind, and encouraging. It's really wonderful.
Have fun, you've got me thinking I should do it again!!