Currently I'm watching couple of shows during the week, I consider them to be "must-sees," but others probably disagree—that's fine.
I'm going to start you off with a few shows that aren't really series, but rather, competition-based TV shows such as: Top Chef, Hell's Kitchen and Top Shot. I also have become very fond of American Pickers, Pawn Stars and Ax Men, all of which happen to be on the History channel. It's safe to say some of my favorite shows are on History.
One of my favorites is Party Down (season 2) on Starz network. The show is completely mad at times, and offers up so many awkward moments and hilarity that I consider it a must-see. Although, if you're easily offended by sexual references, then I say stay away—far away.
Another that I really enjoy watching is Royal Pains (season 2) on USA network. The show is so easy to watch because it's not a violent or graphic show. It's really accessible and fun to watch with the family. It also offers up laughs and some romance. A good medical show, I think.
I recently finished off season 2 of Brotherhood. I really think this show is a sleeper. But sadly, the show ended in '08. I think it's still a good watch regardless of the cancellation.
In all honesty, I'm really biding my time, waiting for season 5 of Dexter. I mean, who isn't, right?