NBC announced today the previews and premieres of its new Fall 2011 primetime schedule beginning Tuesday, September 13 with new episodes of “Parenthood” -- following the final performance episode of “America’s Got Talent” -- and continuing the week of September 19 with the Monday debuts of “The Sing-Off” and new drama “The Playboy Club” on that date. On Wednesday, September 14, the new comedies “Up All Night” (10-10:30 p.m. ET) and “Free Agents” (10:30-11 p.m. ET) will preview following the season finale of “America’s Got Talent.” Both series will premiere in their regular day and time on Wednesday, September 21 (8-8:30 p.m. ET and 8:30-9 p.m. ET, respectively). The debuts also include the network’s other highly anticipated new series -- “Prime Suspect,” “Whitney” and “Grimm” -- that will continue through October 21 when NBC rolls out its Friday-night lineup that includes “Grimm” (9-10 p.m. ET). In addition, the start of the regular season of “Sunday Night Football” will debut...