Season four of The Wire just started, but I've got a season five wishlist item to share. I'd love to see an entire season that flashes back to Stringer Bell and Avon Barksdale establishng their operation, say 5-6 years before the start of season one. Maybe we'd also get to see McNulty's days in the Western with Bunny, Daniels' dark days, Bubs getting hooked on the junk, some backstory on The Greek, a bit of the Sobotka clan, and more Omar (there's never enough Omar). This isn't unprecendented; The Godfather: Part II followed the first movie's saga of an aging gangster and his three sons with a look at how Vito Corleone's operation came to be. With the way they've handled The Wire so far, I think the show's creators could pull off something similar in effect and acclaim.
(Now that I think about it, they're sort of doing that this season anyway. Marlo is kind of a young Avon and in the young school kids, we get a look at drug dealers in the making. Not related at all, but the best line of the series so far is from Clay Davis in the second episode of the 4th season: "Sheeeeeeeeeeeeeiiiiiiiiiiiiit." Laughed my ass off.)