Brightest Young Things suggests the Cottage as a perfect spot for a day date in their 2012 Urban Picnic Guide.
“Grab your picnic gear and put on your history helmet because you’re going to learn in one of the District’s most scenic spots. Make a day of your trip to President Lincoln’s country home, where he’d escape the pressures of the presidency and all that pesky buggy traffic. Admission gets you access to the picnic facilities behind the education center. [H]idden historical gem. Makes for a perfect day day, we promise.”
Take a look at the full guide: http://brightestyoungthings.com/articles/dc-urban-picnic-guide-2012-edition.htm.