The American College of Trust and Estate Counsel (ACTEC) has released the third edition of its book with sample engagement letters: Engagement Letters A Guide for Practitioners (3rd ed. 2017). It is also available as a free pdf. These samples can be useful when teaching Chapter 2, Section III on Creating the Lawyer-Client Relationship. (Hat Tip to the Elder Law Prof Blog for this news item.)
P.S. For those who don’t know, ACTEC has also issued commentaries on the Model Rules.