The happiness problems are basically solved when you get to the buildings that improve happiness. They come too late. There is a large part of the game where you're trying to curb growth. In Civ IV you could whip and improve the happiness of the city more easily. I think they need to add early happiness buildings to smoothen it out. The granary or the monument would be good choices I feel for extra happiness. Perhaps add one happiness for a garrisoned unit.