pinwheels! we likes pinwheels
or, a star is born

or a galaxy, for that matter.
k. gonna give ya another idea just cause the client sounds like he's ripping you a bit... black holes! paint a black brush on a black background and give that to him

seriously, though...well, sorta serious... take your original (ya, i know you wanted a critique, but i'm off and running now), the one with the single circle, and go the other way. instead of filling middle and twirling and so on, use the circle to paint AROUND the 'hole', the black in the middle. then just go creative with 'debris', add a starfield as a backdrop, and voila', instant black hole! oh, and for real dramatica, add a white 'starfish' effect, and warp/bend the 'arms' to the middle around the black hole. or, instead of a starfish, do a 'field of light'. remember, black holes bend light. then add in the starship Enterpri....oh wait, that's something else. never mind
pinwheels! i like it
Craig