I've never noticed them to stop being cute. Even when they're in their "tweens", there's still something adorable, though at that point they really don't resemble either chicks OR chickens.
(but yeah, when their poop starts to smell, the cute factor does diminish....)
It depends a lot on the breed and the source as well. For instance, most feed store chicks are going to be production birds that are bred to feather out and mature quickly. Breeder and slower growing varieties may take a lot longer. Last spring I has some breeder Welsummers and feed store Sex Links that I picked up the same day. At five weeks, the Sex Links were well feathered and ready for to take on the world. One very slow Welsummer cockerel was just starting to feather up on his back at that point.
Mine are adorable from the moment they pop their little, wet heads out of their shells and until the very last day they take a breath.
However, day old chicks are best for photos because they will stand there calmly for photo shoots. Little feathers on their wings during the first week are also good for pictures, but the chicks are so much more active by then it WILL take a professional (or very good amateur with a FAST camera lens) to get the best shots.
Yeah, if want easy to pose day old chicks, you'll want to find true day olds that just hatched. 48 hours post hatch and they don't sit still very well anymore.