I always preferred to see much older girls play Annie- I thought they just dug into the part in the way that 10 and 11 year olds rarely did. As long as they're within the height restriction, it works.
Someone did tell me there was a 19 year old orphan in the original London production at one stage, but the only time I recall seeing adult orphans was in a UK tour about 8 years ago and I thought they looked terrible. Although they were small adults, at least one of them was obviously an adult. There's just something in twenty two year olds that can never be a 12 year old- certainly not in the middle of genuine 12 year olds. Ok, it saves money, saves child wrangling, saves tutoring,but if you cant afford to do the show properly or cant be bothered to do it properly, dont do it at all!(something Id love to say to a lot of theatre managements in the UK right now!)