TV tonight: 'Men,' 'Ethel,' 'Elementary'

• Miley Cyrus is a guest on 'Two and a Half Men'
• HBO airs Rory Kennedy's documentary about her mother, 'Ethel'
• Holmes gets a new nemesis on 'Elementary'

Two and a Half Men
CBS, 8:30 ET/PT

Need proof that Miley Cyrus is determined to leave her Hannah Montana Disney kid-show days behind? She guests tonight on Two and a Half Men, a sitcom that, both because of and despite the adolescent nature of most of its humor, is about as adults-only as network comedies get. And these days, those adults had better have an incredibly high taste threshold for smutty jokes.

Ethel
HBO, 9 ET/PT

In a world where so many so-called celebrities overshare, a few people still cherish their privacy — including some, like Ethel Kennedy, who actually have fascinating stories to tell and lives to celebrate. Tonight, this normally reticent woman briefly lets you into that life as Robert Kennedy's wife and widow with Ethel, a documentary directed by her daughter, Rory Kennedy. As the name of that director would indicate, however, those seeking an expose should look elsewhere.

Elementary
CBS, 10 ET/PT

Is Holmes about to pick up a new nemesis? Could be, to judge from tonight's solidly entertaining outing that finds Holmes (Jonny Lee Miller) and Watson (Lucy Liu) on the trail of a serial killer. The show could still do more to distinguish Holmes from TV's other detectives (though to be fair, part of the problem is that so many of those detectives borrow from Sherlock Holmes). Still, as long as Miller and Liu are on screen together, and they are for most of the hour, Elementary continues to hold its place as one of fall's most promising shows.