At around $250 per copy, Monitaly's cotton summer shirts are a bit pricey. And if not worth buying, they are at least worth studying as examples of how to get the small details right for an ideal summer shirt:

1. Collar: Unstructured, wide point, lies completely flat. One step away from pajamas. None of those dinky little button-down collars here.
2. Hem: Straight, not curved. You wouldn't even think of tucking it in.
3. Print: Casual and yet somewhat elegant. A bit FU, but at the same time, almost baroque in an old-world continental kind of way.

It's hard to tell due to the rather busy patterns but they also have small waist pockets as an interesting detail. Available at Bloomingdales and inexplicably also at Urban Outfitters.