Hi Becca,
Without seeing pictures of the closets it is hard to give an exact answer. However, being a father of 4 small chidren (7,5, and 3 year old twins) I can tell you what has worked for us.
In their closets I used adjustable metal shelves. The type where you mount a track in the back wall of the closet and then inserts support arms where ever you want shelves. The nice thing about this with kids is that you can set the height so that some clothes can hang and, as they get bigger, just keep raising the shelves.
Another good item to get is an under the bed plastic container. Well, several actually. These are low plastic storage bins with lids that are meant to be slid under beds. We use these for off season clothing and shoes.
If you can upload the link to some pictures of the closets I might be able to give you an answer more specific to your needs.
I hope this helps!
Jim
