you really do 12" spacing for decks 16" would be fine no? I thought that was pretty much the standard and I put the decking on 45 Degree angle(wishbone) and just doubled up the center joist and it's solid as a rock!!! no bounce at all. I just I did mine 1 1/2 yrs ago and I just used 2X10 instead of 2X8. My buddy who is a contractor did his same as me only he used 2x8 and is a simialar size to mine but wanted to save few bucks and his has a little bounce in the middle.

But anyway your right!!! do it right!! and besides I believe most state are 66.9 brix anyway I know NH, VT, and NY are don't know about the rest.