well i'd make it reversible if possible. one "older" side for later.

Thanks everyone for your suggestions. I appreicate each one.

This could easily be done in flannels. It's easy to adjust the size by cutting the strips wider/narrower and shorter/longer. And you only need three fabrics.

http://www.maryquilts.com/quick-strippie/

I made my DGD a Sunbonnet Sue and now my other one wants one too. They are cute for little girls, but also as they get older. My 27 year old still loves hers. They are really easy to make (It was the first quilt I ever made)

I recently did one for my niece. She's a little older (9). I did pinwheels/solids. The pinwheels 'flowing' kind of like a kite tail throughout the top. Used colors in her room as DB and DSIL said it was staying those colors for a LONG time. Used flannel on the back only. FWIW I would highly recommend Moda Marbles flannel. It's beautiful! I'm not really fond of their cotton marbles but the flannel was delicious. And definitely prewash as others suggested.