Check out Flylady.com---Especially you QuinnP! THE guide to getting your life in order. Also has a book about weight loss that I recommend to a lot of people.
I love your ideas OP.
Ema, Maybe you could just point out that there just isn't ROOM, and to make room for new things in our lives we have to get rid of the old. I do that with my closet, I can't have new, nice clothes that fit if I insist on keeping all the crap clothes. For my children we have a giant cabinet with 8 baskets. All the stuff needs to fit in there. If we can't fit it in we have to purge before we get new stuff. We do have play areas in their rooms and stuff that are not quite so organized but this helps. I also have my 6 year old that draws 1000 pictures a day sort her stuff into keep, send or recycle. That way the relatives get drawings, we have a few to keep but most get recycled. She used to really hang on to stuff but is better now.