This week’s open house picks are four townhouses in Clinton Hill, Crown Heights, Midwood and Flatlands. All of them have preserved period features and three could use at least some modest updating in parts. They range in price from $785,000 for a two-family brick row house in move-in condition with a garage in Flatlands to $1.796 million for an Anglo-Italianate brownstone in Clinton Hill with marble mantels.