Lulilu......honestly, you can't get any more casual than Shopmom! AND I live in the fashion-disaster mecca of the West Coast! Berkeley, California! Where Birkinstocks reign King of footwear!
My entire Hermes collection consists of 90% Kelly's. Seriously. I think you can totally rock a Kelly with casual clothes.......if you are a bit nervous about it but would love to have a Kelly you can try a BJ in souple for example. But listen, I've got a vintage Etrusque Croc Kelly coming (let's just hope its this coming week or I'm going to slit my left wrist.....) and I'm going to wear that baby with jeans, jeans, and more jeans. And THAT'S a pretty "formal" bag! I'm a firm believer that Kelly's can either dress up or dress down....as long as you're pulled together in some way, you don't have to worry. For example, you can totally get away with a pair of nice jeans, white cotton shirt and flats and a Kelly. Or nice jeans, pullover sweater, scarf, heels and a Kelly. Can you tell I love those Kelly's????
Anyway, I'm all for a Kelly especially if you already own a beautiful Birkin or two (or more!)....you might just be ready!