barbarian gone dragon disciple is my vote.
Another way to do it is go barbarian, then bard, and into DD
I like the melee-heavy Dragon Disciple Builds. Barbarian has problems Casting while Raging, but you can pre-buff for the most part, de-emphasize high CHA and DCs to focus on buff/utility spells, and still drop Rage when you need to Cast mid-battle, maybe with a 'Rage Cycling'/Fatigue Negation strategy so that doesn't screw you up too much. Or go with Fighter/Paladin/etc and there is no Rage/Casting conflict. The Magical Knack Trait that boosts CL (not exceeding char level) is nice for this build, especially for durations. As mentioned, Bard as the entry into DD is nice since you can still wear armor, it's too bad there isn't an official 'Battle Sorceror' Archetype in PRPG (like 3.5 Unearthed Arcana). Or you can use Celestial Armor (15% ASF, reducable to 5% with 1 Arcane Armor Training Feat, using Swift Action). Or Mage Armor and Shield spells.
Crossblooded is attractive, but the spells known loss can be harsh. The only characters I see pulling it off well would be Humans with their Racial Favored Class bonus (spells known), and/or using Expanded Arcana Feats to get more Spells Known. Also, using Pages of Spell Knowledge/Rings to get more spells known is a good idea, along with scrolls/wands for stuff whose DC or CL you don't care about as much.
Eldritch Heritage should always be considered in lieu of Crossblooded, albeit you don't get both Bonus Spell Lists/Feat Lists and you miss out on Arcana and delay progression in Bloodline Abilities.
sorry, remembering build from non-PFS game.
i'm clearly in the minority, but my vote would be for the rime-bloded viking. you could easily pick up the eldritch heritage feats for the draconic bloodline too, if you wanted.
if you do decide to go the dragon disciple route...
straight sorcerer is not optimal but it's not so bad that you'll be a burden (by 12th level you'll be bummed that you're just finally getting 5th level spells, but you'll be a lot more durable than most sorcerers)- if you're gonna do it you could really embrace the theme and pick up eldritch heritage[arcane] and improved familiar, so you can have a pseudo- or tidepool dragon familiar.
the barbarian build is much more effective, but a lot less caster-y. if you decide to go this route think about taking Archaeologist levels for the spontaneous casting (its a bard archetype that can self buff while raging), and making him/her a human with the Heart of the Fields trait- that allows you to just not become fatigued when you should 1/day... couple that with the moment of clarity rage power and you've got a couple options if the need to cast during combat arises. in that build you don't need more than 13-14 cha and you'll learn buffs and maybe some healing instead of offensive/control spells (cause your DCs will suck). if you want to do a lot of natural attacking, you might want it slighlty higher (for more rounds of claws) but the real trick is to take eldritch heritage[draconic] to double the number of rounds you have claws (both the feat and the Blood of Dragons ability grant you bloodline powers, but not the bloodline so the ability does not rule out the feat, but they don't stack levels- so if you took improved heritage you'd get another breath attack but wouldn't combine any levels to determine damage dice).
I always have a few words of advice for PFS play. With magical Knack out, it is difficult to maintain spell levels, and full caster DD's really need to get whatever benefit they want. If you want to blast, I recommend keeping your caster level up. Spell Expertise can be your bet at level 1 if you are human, then you can take a couple levels of something else and still keep up with your damage. Your save DC's are going to be low, but you should be okay, and just move your spell up as you go. Shocking Grasp is a great idea, as it will be useful throughout your career. As far as spells are concerned, fire is your best bet, followed by electricity. Acid and Cold are only good with extra help, Rime Spell or Noxious Bite (which I am pretty sure isn't legal for PFS).
One or two levels of Barbarian are really good, but if you go that route, you probably don't want to do an abundance of blasting, so you should stick with buff spells. Enlarge person, Mage Armor, True Strike, and possibly Feather Fall. The final two in that list don't trigger ASF, so you can wear armor at lower level for them, so you aren't as squishy. I also recommend a reach weapon, as both True Strike and Enlarge person are great for that, Enlarge person gives you 20' reach, True Strike gives you near foolproof combat maneuvers at range so you don't provoke as many attacks of opportunity. Also, you can get various kinds of materials for your reach weapons to better bypass DR.
If you take two levels of Barbarian, you don't have to worry about getting 2nd level spells until you hit level 6 or 7. By then, you will have plenty of time to feel out your style of play and look at spells. Feats are more important, and once you figure those out, you are golden. But you have a good start, you have your concepts down. Just build it from there.
If you haven't read my guide, I recommend it, even though it is focused on non PFS play. There are some good ideas discussed there. There's even a suggested spell list on the bottom.
if the spells come from bard none of them will trigger ASF (if you limit yourself to light armor- like a mithril breastplate, since barb grants medium armor proficiency), and that is enough to qualify for DD. spells should be focused on buffs with a little divination and healing; avoid damage and control- your DCs will be too low and your max spell level will be way behind straight casters. your damage will come from melee (and occasional breath weapons)... start with a good strength, get the bonus from rage, and from DD levels to be really strong- use skills and divination to try to get the drop on enemies, throw on a couple buff spells and Archaeologist's Luck and start swinging. after combat, help heal and enjoy being badass.
to help with the most recent question, here's a few suggestions:
level 1: moment of greatness, expeditious retreat, anticipate peril, vanish, cure light wounds
level 2: heroism, allegro (which will work with Archaeologist's Luck, but not lingering performance), tactical accumen, blur, cure moderate wounds