Park and stroll through downtown 10 a.m.-5 p.m. Saturday, Dec. 3, as The Petaluma Downtown Association stages its annual Open House. Take a horse and carriage ride, have some hot apple cider, take a photo with Santa. Then stroll down to the Petaluma Yacht Club at the Turning Basin for the 6 p.m. Holiday Lighted Boat Parade. More information: petalumadowntown.com.