It is advisable to increase the rigidity and strength of your deck’s rim or perimeter in order to reduce bounce and provide a solid foundation for your rail system.  This can be accomplished in a couple of ways.  You may want to install double rim joists across long sections to respond to the flexibility of the material.  Also take advantage of your extra materials by installing blocking around the perimeter.  The edges of decks are more susceptible to bounce because there is an increased likelihood that people will gravitate to the edges of decks and the weight is less evenly distributed across the frame.  The perimeter is also where rails are attached to the deck frame.  Using 12” on center joist spacing will strengthen the frame throughout the deck.