While I doubt I'm one of Samtemdo's colleagues, I'll second Babylon 5. It was a show planned entirely in advance- the story ran for five years, and the show had to end after the fifth season, which is why it took so damn long to get a network to agree to air it. The show's creator wrote 92 of the 110 episodes; more so than almost any mainstream TV show, it was his baby, and it shows, both in the show's quality and consistency, and the toll it took on him. The idea of long, multiseason plot arcs isn't really a rare thing anymore (or so I'm told; I don't watch much TV), but B5 was definitely a pioneer in that field. And as wonderful as it is the first time around, a rewatching will show you not only nods and hints toward future elements, but earlier connections and even entire sideplots you missed the first time. And though few will catch it on the first runthrough (I certainly didn't), the music is absolutely fantastic; I ended up buying several of the CDs.
There are a couple of caveats, though: the special effects do look dated (B5 was also a pioneer in TV CGI, and the cutting edge of 1994 isn't so impressive now); the fanbase can be a little rabid ("yes, the show was excellent; no, it's not without its flaws or beyond criticism; and- hey! Stop biting my leg!"); and, well, you should know going in that this is neither a utopian Star Trek-style depiction of the future, nor a dystopian Twilight Zone-style one; bastardry and heroism both abound, sometimes in the same character, and occasionally at the same time. You don't see that often in sci-fi, but it's definitely worth a watch.
