Take the hardest trail of the whole tour, and take Novices along it, on the very first day.

 Doh!

(we don't do this anymore - we've dropped the tricky first day trail near Chiang Mai)

It's worth noting however, that the trails change year on year.  The Monsoon rains alter the routes, sometimes quite significantly.  What is easy one year, may turn out to really tricky, or even impassable the following year.