I wish I could say we worked the theme a bit more, but sadly we did not... I printed up the invites on some fun invitation paper I found at the Paper Outlet (on San Pablo? Berkeley/Oakland border) and explained the concept. The decor was pink (that was her color) but it was otherwise pretty mellow and low key. We had the party at my parents' house, and the theme worked out well as it was a fair mix of older family/friends, and my sister's friends. My aunt made up little lavender sachets that we topped with a pink-wrapped chocolate from Michael Mischer (in Oakland) for favors.
We also did the recipe cards--great fun!
You could get really into it though--maybe combine it with a cooking class? Or have kitchen-ey favors? Make it a pajama party?