When you name a guardian in a will, remember what sort of an impact adding family members will do to their family and provide for it...  a bigger house, car, an addition to the house all may be required for the people who will guard your most important assets... your children.

Be careful naming the person to make difficult family decisions.  Most of my clients find it well worth the money to appoint independent professionals and pay them to make those decisions, rather than putting a loved one in the middle of making tough decisions regarding another loved one.  Imagine the next family gathering where your one son, the  Trustee runs into the  other child or family member who he has denied a request for money because he feels it will be used irresponsibly. 

Independent professionals charge but they don't lose sleep at night over carrying out your wishes.