SEASON PREMIERE: Season 6 begins tonight with a two-hour premiere, and there’s a lot to say about it. AMC and series creator Matthew Weiner, though, have asked for reviewers to be especially circumspect, so let’s just say it’s nice that Mad Men is back, and, by the time the two-hour premiere is over, you’ll be happy to have begun spending time with these characters again. What characters, and what time, I won’t say. For more details, vague and otherwise, see Eric Go