Orianna is a high damage character with lots of range and very good escape ability. I play her mid lane, but she can be played bot lane with a carry, although i do not recommend it, at least with my build.

straight damage.... whats not to love? you get all the other states u need from your items, this is for early game (quins and yellows) damage and late game (blues and reds). unfortunately i have not tried cool down reduction blues, i just like my damage too much.

Standard caster build, only thing i can see a problem with is "i want to level faster in lane" so then just pick up the 2 points in Awareness. The only reason i like the mana instead is because of archangels.

I have played a lot of orianna and always had just 1 problem. Negatron cloaks. as soon as they see how much damage I'm pumping out they just grab one and now I'm just a lousy AP carry. I have tried to play with sorcerer's shoes, but i need the cool down reduction from Lucidity. With this build there is a very very nice balance once u reach mid game, my runes are giving me AP, my boots CD reduction, and my void staff, runes, and masteries are giving me Spell pen. This gives me a nice balance, im able to spam my spells, not go oom because of tear and do some nice damage that is very helpful in teams fights, which should be happening around level 10.
I have left the last item space open because it will be a situational item. With just these items you will have tons of AP, good CD reduction, and enough spell pen to hurt tanks, so the last item is up to you, RoA is a decent option.

Flash and Ignite, ive just always used these for most of my casters i play, little extra burst and some survivability. I can see how Flash, teleport would be useful aswell, i am a big fan of teleport. as far as the other spells i dont see much use, unless you love exhaust, but your dissonance will get you out of any situation better then your exhaust will.

Pros:
-Great balance mid game
-superior damage early game
-Has alot of support spells for easy assists
-great range
-can zone, if youre good enough
-good escape tools
-great farming (at around level 8 you should be able to kill all the caster minis with just a Q and W)
Cons
-squishy until rylai's
-ALL YOUR DAMAGE IS A SKILL SHOT (hard to play)
-not the easiest champion to play