Decks, Patios, Porches and Docks - Deck joist size

This is my third deck I have built. The first two were just easy rectangles and only a few feet off the ground. The one I am doing now is about 9' off the ground. Plans I created from the store puts the first beam at 8' from the house because of notch for the stairs (plan shows 6' out but I can't do that because of a concrete patio). Then a second beam is 4' from there with a 2' cantilever for a total length of 14' of deck. I will be using 12" footings, 6 x 6 posts and a 2 x 10 beam. I planed on using 2 x 10's for the joists but now I am second guessing myself and am thinking I'll just do 2 x 8's. What are your thoughts? Are 2 x 10's worth the little extra cost?

I built a second story deck awhile ago but the plans were a little different. The four 12" footings were the same but there was no notch for the stairs. I stood four 4x4s on the footings but they went 3 feet higher than the floor and were used as part of the railings. That eliminated the need for a ledger board against the house, although I used 2 L shaped brackets for extra support. The idea being that no water can collect there since the entire deck was a few inches away. 2x10s went between each 4x4 all the way around creating a box. The stringers for the stairs leaned against one of the 2x10s. Then I used 2x8s for the joists and 5/4 decking. The deck was 10x10.

So to answer your question, I would say the 2x8s are good enough. Don't forget to use Zmax ticos since the chemical in presurre treated wood has changed.

As a professional, rule of thumb we use: 6' span or less 2x6
8' span or less 2x8
10' > 2x10
12' > 2x12
That is if the plans are not stamped by an engineer.