A good source for building resource information by: Editor - Rich Bergman
Sorry for the delay in responding. I think one of the first places you might go to is the American Wood Council at www.awc.org.
They have a ton of great resource material which has span tables done up by experts that are referred to in building codes. I do think that is the most efficient direction I can give you.
They also have a great new publication on deck building called DCA 6 which sells for about $10 and has super comments in it including joist and beams spans and spacing.
I refer to many of their publications often as they are done right.
I am building a 10'x12'deck (not attached to a ledger board). My plan was to pour concrete footings, then run doubled up 2x8 beams setting on the footings