C.,
My 4 year old, who just gave up naps a few months ago, is allowed to read a book in bed, be it a sticker book and play with the stickers or what we call a color book, which is one of those books that have the wipe board, etchesketch thing attached. He is also allowed to play with his little cars in bed. The rules are he must stay in bed, lights off, although its not too dark in there except for rainy days. He has a little box of a few toys and books he keeps on his bed, therefore he doesn't need to get out of bed at all. If he stays in bed and is quiet, he gets a sticker on his chart and when the chart is filled up he gets to pick out a new toy to put in the box for future quiet times.
Hope that all makes sense,
K.