I'm trying to play catch-up also. The more current pictures seem so much more exciting to me. I am making myself do at least one old LO for every 2 "current" LO's I do. If I don't, and with the amount of pictures I take, I will never get "caught up!" My youngest (the deprived one, of course) is 9. I just came across some Halloween pics when he was 2 and can't quit smiling and 'awwing' over them now. Maybe the more I dig, the more exciting and memorable the older ones will become.
The motivation for me is finishing a page and seeing the smiles on my kids' faces. They love to see what I do with their pictures!