Curious viewers showed up in big numbers Wednesday night to see Gov. Sarah Palin’s first spin on the big dance floor, with the Republican VP nominee drawing nearly as many viewers as Barack Obama the previous week.

Nielsen estimates that an average aud of 37.2 million viewers were watching on various broadcast and cable outlets from 10 to 11:15 p.m. ET on Wednesday, with Fox News Channel leading the way and drawing its largest aud on record for a convention night.

The collective crowd was more than 50% larger than what the Democratic vice presidential nominee, Sen. Joe Biden, drew one week earlier (24 million), and it was nearly as big as the audience that tuned in to watch Sen. Obama accept the Democratic nomination for president last Thursday (38.4 million).

Auds were clearly interested in hearing the young voices of this year’s election. Obama, of course, is the first African-American presidential nominee of a major political party, and Palin is only the second woman to be a major party’s choice for vice president.

Fox News drew the largest aud (9.21 million), followed by CNN (6.18 million), ABC (5.90 million) and MSNBC (3.37 million). Ratings were not released for NBC or CBS, which opted to air no national advertising during its coverage, while PBS averaged an estimated 3.2 million viewers for the entire duration of primetime, though its numbers were not broken out for the Palin speech.

The big showing for Fox marked a reversal of the audience makeup for Obama’s speech last week, when CNN topped all networks with 8.1 million to 4.22 million for Fox News and 4.09 million for MSNBC. FNC says it drew more viewers than on any other convention night in its history, and Wednesday repped its third most-watched night overall.

It’s interesting to look at the audience compositions for the Obama and Palin speeches since the overall audiences were relatively similar.

Nielsen reports that Obama held a 13% advantage over Palin among adults 18-49 (16.0 million to 14.1 million) and more than doubled or tripled the Republican’s turnout among blacks (7.5 million to 3.0 million) and Hispanics (5.2 million to 1.4 million), respectively.

The Palin speech, meanwhile, outdrew Obama’s among adults 55 and older (17.9 million to 16.5 million) and whites (31.9 million to 27.0 million).

On the entertainment programming side, Wednesday also saw a pair of returning shows kick off their season: Fox’s “Bones” and CW’s “America’s Next Top Model.”

The two-hour “Bones” (3.3 rating/9 share in 18-49, 9.74 million viewers overall) was the night’s top program in demos, matching its premiere score of a year ago and delivering its largest overall audience since its series preem in September 2005. “Bones” will regularly air at 8 p.m. on Wednesdays, followed by the half-hours ” ‘Til Death” and “Do Not Disturb.”

At CW, “America’s Next Top Model” (1.7/5 in 18-49, 3.51m) had its lowest preem scores in its 11 cycles to date, though it tied with “Bones” as the night’s top draw in women 18-34 (3.0/9). “Model” faced tough competish from a two-hour “America’s Got Talent” on NBC (2.7/7, 10.25m) and Bravo’s “Project Runway” (1.7/4, 3.26m).

“Model’s” solid bow continued a good week for CW, which even managed to elicit a vote of confidence from top affil Tribune.

The relationship between Tribune and the CW remains testy — the station group has been stripping the CW’s name off its affiliates in recent weeks (Daily Variety, Sept. 2) — but chief operating officer Randy Michaels said the company was “ecstatic with the terrific launch numbers.”

“Association with the burgeoning CW brand is an asset to any station group, including our own,” Michaels said. “We have had many local success stories this week.”

And in national ratings for Tuesday, delayed a day by Nielsen due to the Monday holiday, ABC Family’s “The Secret Life of the American Teenager” (1.3/4 in 18-49, 3.55m) had another impressive showing.

With its penultimate episode of the season, “Teenager” hit series highs in women 18-34 (2.7/8) and women 18-49 (2.1/6) and tied the premiere of CW’s “90210” head to head among persons 12-34 (2.6/8).