I happen to be a fan of these letters. I always try to make ours creative, funny, and only one sheet of paper with normal font. For those of you who like to write them here are some of the formats I've done over the last few years:
*one year we got a new kitten and I wrote the entire letter from the perspecitve of the cat
*the year that Who Wants to be a Millionnare Play It closed down, I wrote the letter in Who's Wants...question form. I would even write like "you say B., is that your final answer....yes, you're right we did..yadda yadda. I even added a few life lines into the letter.
*this year, with the presidential election, I paired the entire family up (including pets) into various presidential "tickets" each with a description of their positions on various issues while hitting highlights of the year. On one ticket, I reported that the vice-presidential candidate (our cat) was a controvertial choice because she hadn't been thoroughly "vet"ted but that she brought foriegn-policy experience as she reported with a paw wave and a wink that she could see Tennessee from our house.
*One particularly busy year, I pretended that letter was an attraction description of the various "rides" at "Six Flags over Murray"(the town we live in). I included the pre-teen rollercoaster, etc.
If anyone wants to see these because they could be adapted for other families, just PM me....