Concerts in the Park supporters found their way through Gypsy Sally’s to the Vinyl Lounge down at the Georgetown waterfront April 14 to chill with classic tunes, bar food, beer and the music of singer-guitarist Steve Siekkinen. “More cowbell,“ announced the T-shirt of John Rentzepis, the public safety chair of the Citizens Association of Georgetown. Concerts in the Park is a CAG program — with these summer dates: May 22, June 19 (Fathers’ Day) and July 10.