Nicely done!
Out of curiosity, have you taken either your new min or max calculations and looked at trending?
It would be interesting to look at the last 20 years or so with your new eyeglasses. ;-)
The BLS didn't start tracking those not in the labor, by who did or did not want to work, until 1994. However, I just created an (unadjusted) table comparing the Annual Change in the Labor Force from 1947 to 2011. It's interesting to note that aside from the past three years (2009, 2010, and 2011), the last time there was a net decline in the Labor Force was in 1951. However, the decline in 1951 was due to a general decline in the non-Institutional Civilian Population. So that makes Obama's misrepresentation unprecedented. It's outright manipulation.
Here's a link to my spreadsheet, with data pulled directly from the BLS: Civilian Population vs. Labor Force - 1947 to 2011.