Sideboard Shortlist:
Destructive Revelry
Arbor Colossus
Xenagos
Seismic rupture
Hornet nest
Roast
Nissa
Silumgar's Scorn
Negate
Wild slash

Been cranking on thoughts for this deck, so I'm gonna mind dump here for you and see what you think.


Matchups
I'm just gonna look at the 3 general archetypes of aggro, midrange, and control.
Aggro - This isn't necessarily a bad matchup, but I do think this deck is going to need some more controlly options to get through the early game. Rattleclaw is alright here, although Caryatid would be better as an un-burnable wall for them to run into. Your top end dragons are simply going to outclass whatever they may be playing, and the token that sarkhan can make when he drops will mean you get value out of him even if they run wide. I think you run on the bad side of this matchup as is, though. The mana dorks may slow down something like mono-red enough for you to deploy your power, but against an aggro/midrange deck you look a bit weak. I would seriously consider cutting the surrak's for more burn options to control the early game until you can start deploying your threats and create a stable board to drop xenagos/sarkhan onto. Tokens can also be an issue, but i think the draconic roars help enough game 1 to make it 50/50 and a few sweeper type effects in the sideboard will shore that up.


Midrange - We have to deal with the elephant in the room, first...which happens to be a rhino. Right now, you have 0 answers for siege rhino. Going back to the aggro suggestion of some more early game burn, I think making the 2 surraks into 2 roast will shore up both issues.
I like this deck against the control side of midrange, because it's fairly threat dense and if you drop a sarkhan onto a stable board you'll have a leg up on the card advantage game. I actually really like Rattleclaw over Caryatid here, because at worst it eats a removal spell, and at best it can get in a few passable attacks if they get off to a slow start.


Control - Sarkhan and Xenagos are solid here, because Sarkhan can produce a threat and then remain a must answer due to helping with your card advantage. Xenagos creating tokens for 0 loyalty also makes him a must answer that you at the very least push a token out with if he sticks. This is really where rattleclaw shines, because 2 point hits add up pretty decently, and should be able to draw some removal out of their hand. 


Overall I like the deck, and my major input amounts to swap out surrak for roast. 


The only other thing that comes to mind is dealing with the mirror (an exact mirror is unlikely, but a GR Dragons deck is very likely). If we can find space, the two answers that address this best (in my mind) are arbor colossus and disdainful stroke. Arbor colossus would provide another big body to straight up trump anything aggro is playing, plus totally shut down a stormbreath. I'm suggesting disdainful stroke over silumgar's scorn because of mana color issues, and I think that the only creatures you're really worried about are other dragons (which get nailed by disdainful stroke). Not sure what you would cut maindeck past surrak, though. Possibly cut 2 thunderbreaks for 2 disdainful strokes?