What a fun project! I've been writing a few family stories as well and the best way to discover what format works is to try it. I've sold a few to magazines. None were PB material--it really is a different animal. I'm finding that a collection of short stories is the best for the way I'm writing them (then again, I am a short story writer, so it's something I do well, thinking in vignettes). I know a few people who have written novelizations. Hattie Big Sky by Kirby Larsen comes to mind. Good luck!