This is an issue for me also and while I have taken measures to improve the situation it still could be better.
I have a shelf like this
http://compare.ebay.com/like/1306087...Types&var=sbar that I put board books on for the babies and then I have dishpans that I labeled for with categories and photos of the different styles of books that are placed on the bottom bookshelves for the older toddlers with regular books stacked on the upper shelves for the school agers.
This does help tremendously and I have an area that is semi secluded in a comfy corner that I find the babies really don't go to often.