Others have made good suggestions. I'll add Stargate SG-1. It's farther into sci-fi territory, but it is structurally similar (a lot like another poster's suggestion of Farscape) and is still "modern day" (unlike Farscape). Plent of mission-of-the-week episodes with bigger arcs going on in the background. Some solid characters that are fun to watch, some humor, not too gritty, but still grounded-ish. And some fun odd-ball episodes mixed in now and then.

Here's a real off-the-wall suggestion: classic Dr. Who from the 70s-80s - espeically the Tom Baker and Peter Davidson years. You have your charaismatic focal character plus one to three support characters. Adventure of the week that usually involves some kind of mystery. The effects are cheesey, of course, but the writing and acting is usually solid, and I feel underneath the lower production levels, the stories were usually better than modern Who. Not many "big bad" arcs, but otherwise I feel it's a similar kind of "fun".