While grilling will get you a rapid-fire crust on your steak with all those delightfully crisp, on-the-verge-of-burnt bits and a good smoky flavor, I find that the even golden brown crust you can develop in a hot cast-iron pan really accentuates the flavor of the beef itself, letting it shine.
Indeed, pan-seared steaks have several distinct advantages over grilled steaks-enough that there are times when given the two choices, I'll choose pan-seared just for the sake of it.
Summers are made for the grill, but what's a steak lover to do when the weather's too cold and wet to light the suckers up? Just cook them indoors.