With the recent loss in my family, I have seen how those around me are struggling and how a note would be something to treasure. I just wrote a letter to my family incase something like this happens. BUT if only given a few minutes, it would be:
"To my family, I love you so much! I get to go be with the Lord our Savior. Draw close to God, so we can see each other again. Be happy for me."
traveler101 makes a great point: Don't wait to tell people what you think and feel.