Heroes S1 had mystery, awe, and wonder. It also had all kinds of coincidences. These characters were all discovering one another and discovering themselves. It was pretty damn cool. Heroes S3 didn't have anybody discovering anything, unless you want to talk about Claire's love life.

On other topics in this thread, I don't watch Fringe, but I did watch Buffy, and the musical episode of Buffy was absolutely brilliant, as was the "silent" episode. Certainly, Southpark brings in musical numbers every one in a while to much good effect. Suffice to say that it can work.