I just read Pope John Paul II's will online. It reads more like Life Letters, which are letters that I encourage my clients to write to their loved ones to include with their estate planning binder. It's really a valuable gift that you can leave behind. The Pope's includes a lot of encouragement to Catholic believers, as well as his hopes for the world. It thanks various people and declares his faith in God. Of course, yours probably won't look like the Pope's, but you can include information about yourself that you want your kids to know, lessons that you've learned in life that you hope to pass on, values that you've held that you think are really important. You can also include a letter to Guardians that explains the values that you hope your kids will be raised with.
If your attorney doesn't include this with your Estate Planning Binder, it's easy enough to do on your own. Just start writing letters and try to update them every few years. Your loved ones will be glad you did!