Guinan on the case, interesting. They cycled through the whole cast, but skipped Wesley. Then of course, they didn't put in Yar and Pulaski while they were on. I bet we'll see Ro Laren on season 5.
So four seasons in, Picard has made the cover each time (obviously), with Riker twice, and Guinan, Troi, Worf, Data, Crusher once.