Best Bets on TV Tonight

Based on the novel by John Knowles, "A Separate Peace" (7:30 p.m., Showtime) is a new "for-all-ages" movie about prep-school students coming of age as the United States enters World War II. The cast includes Toby Moore, Hume Cronyn (in his final performance) and J Barton.
An awkward 13-year-old (Emma Roberts, niece of Julia Roberts) gets a grip on her daily life through songwriting in the new comedy "Unfabulous" (8 p.m. Nickelodeon).
Nick Lachey joins the cast of "Charmed" (8 p.m., the WB) as it begins a new season. He plays a newspaper columnist who causes hearts to flutter with one of the witches.
On "Play for a Billion" (8 p.m., ABC), 200 contestants get a chance to win $1 billion -- all they have to do is match a randomly chosen six-digit number. (Much more likely is that the last player standing will wind up with the guaranteed top prize of $1 million.) This show is the culmination of a Pepsi sweepstakes promotion that's been running all summer.
The little-remembered "second war for independence" gets some overdue attention in the new documentary "First Invasion: The War of 1812" (9 p.m., History Channel). For the United States, the low point was when the British marched into Washington and burned the White House. But the lopsided U.S. victory in the Battle of New Orleans turned things around.