I've got a 12 year old and we each have an ipad but we haven't found any good games we can play together. Genre can be anything, we're mainly interested in quality co-op games that isn't riddled with IAP's.
Not so much a coop game but olo and letterpress are both nice, I play with my 9 year old. I'll have a look and see what else we've tried.
Get dual browser. You can browse on one half of the screen, whilst your daughter is playing internet games or reading a book.