Pre-Wrath...

Run non-heroic: Shattered Halls (Hellfire), Steamvaults (Coilfang), Sethekk/Shadow Labs (Auchindoun), Arc/Bot/Mech (Tempest Keep).... until you have few upgrades there.
It also helps if you tank toon has some of the tanking quests done, ie group quests in Terrokar/Nagrand/Hellfire along with some of the chains for Shadowmoon Valley and Netherstorm.

Once there's few upgrades in those area's, start with the easier heroics.
Generally these are: Slave Pens/Underbog (Coilfang), Ramparts/Furnace (Hellfire), Mechanar (Tempest Keep).
Sunfire badge rewards are better then Shattrath rewards - initial rewards were close to T4, later rewards close to T5 the sunwell stuff is closer to T6.

Normal instances are mostly elites of whatever level.. say 68-70th mobs.
Heroic will be all 70th mobs, so more experience then 68-70. The trash is a lot harder in heroics, bosses only a little bit harder for the most part.
The bosses add a bit to their loot tables, generally the last boss in the instance has half a dozen extra pieces. They all drop badges.

Not sure if this is what you're asking...