bw100 - 5:24 pm on May 20, 2011 (gmt 0)

the audience being delivered: M18-34, college-educated, from USA ... About 10,000 visitors a month ... business to consumer ... I am looking for national advertisers

As a general interest site, this may not be much traffic for this demographic, and may not be of interest to a national advertiser. However, what is understandably, conspicuously absent is the specific niche audience being delivered. Check the traffic stats of your competitors, and compare yours to theirs. See who their advertisers are.
You may wish to consider your time allocation, and outsource the ad selling while you use the time to build traffic.
Good luck!