Here's some sample letter formats in a word doc
Here's some suggestions:

I love you because ... You are so ... Thank you for ...

Dear God,
I love you because you gave me all this food and a loving mom and lovely grandparents. ~ Jack
Dear God,
Thank you for this life because it is great! You gave me a loving, abundant life and I am grateful.
I hope it will be a long life because it is great! I love you because you gave it to me! ~ Jeremiah

Dear Mom,
I love you because you give me macaroni and cheese and you kiss me and love me. ~ Jack
Dear Mommy,
I love you because you take care of me! I also love you because you, yes you, help me, yes me! ~ Jeremiah
Also from Jeremiah:

Send Love, encouragement, affirmation to someone who needs it!
What organizations do you support that support others?
Send a note through your organization of choice!
The Southern Poverty Law Center: www.SPLCenter.org

Southern Law Center asked for words of encouragement for Jordan Gruver who was brutally beaten by Klansmen.
We send Jordan this message:
Dear Jordan,
We send you Love and strength, courage and healing for what you have suffered. We trust that you are well taken care of now and we are so glad that you survived and thrived through this senseless act of violence. We hope for you that you receive countless senseless acts of kindness so that you're heart is comforted and open to knowing that Love reigns over hate. We are grateful for you and the Southern Law Center in making this injustice known ~ it has given rise to more awareness of the Klan's continued presence and hate crimes. As we pray for you, we also pray for them that they may find healing, compassion, and the power of unconditional Love to overcome hate.
Love,

Laurie Story Vela & New Thought Families

Group Notes:

There was a wall of these colorful hearts at an elementary school we visited in Las Vegas. The hearts were sponsored by the Heart Association and focused on health. Each youth honored someone in their family for a health related reason ~ like quitting smoking. This concept can be adapted to honor anyone and everyone ~
amazing & beautiful!