I'll begin with an explanation of Armor penetration.
Armor Penetration is only effective if you have the damage to multiply. Take into perspective why you would never get a first item Last Whisper. Take into account that Armor Penetration only accounts for AD damage and not AP. These types of runes are ineffective on champions such as Corki or Ezreal because they have AD ratios on Magic damage abilities. Therefore, it would make more sense to use Flat AD Runes instead. As for the champions with a lot more AD damage than the previous two, you could probably get away with it on Graves and Draven since they each have high damage AD abilities. Though take note Armor Penetration is a scaling stat which requires damage to do more damage.
As for your AD seals, don't use AD in your Seals slot. Each slot is dedicated to a specialty of Defense, offense, etc. Seals are meant for Defense in the health or armor department where you will get more bang for your buck.
Your Glyphs should be purely Magic Resist, or Scaling Magic Resist. Other options that spell heavy champions like are half Mana Regen and half Magic Resist. This slot is dedicated to AP related stats so either Magic Resist or AP are best in these slots. More bang for your buck.
As for Quintessences, a general AD-Carry page will consist of 3 Attack Speed Quints since they are more efficient than flat AD Quints now. Since Attack Speed multipliers depend on base attack speed, you may wish to substitute these Quints for Flat AD on Graves for example who has .625 base attack speed compared to Ashe who has .658. It may not look like much, but it'll make a difference late game especially factoring in the multipliers based on level.
A general AD-Carry page will look like this:
Marks: Attack Damage
Seals: Armor or Health
Glyphs: Mana Regen or Magic Resist or Scaling Magic Resist
Quintessences: Attack speed or Attack damage
You may be creative and use a rune page like this in a losing lane:
Marks: Attack Damage
Seals: Health
Glyphs: Magic Resist
Quintessences: 1 Armor, 2 Attack speed.
Hope it helps.