Our successful runs seem to be on par with what other folks are doing. Our best successes seem to be combining several of the strategies here.
1- Intimi tank to grab the dragon and keep her, and the giants that get near her.
2- a ranger using his bow to kite/kill the regular frost giants (not named)
3- 2 dps melee (in our case we had a rogue and another ranger) beating up the red named
4- caster using enervate/flesh-to-stone, we didnt think to use glitterdust so will probably be adding that to our list now. Our caster was also assist healing the kiting ranger with UMD scrolls, so a bard could also fill this role nicely.
5- cleric was keeping everyone alive (obviously), using well placed cometfalls (be careful where ya put em!) to assist damage/crowd-control/kiting depending on what was needed, and using Break Enchantment to get rid of enemy blade barriers as fast as possible.
Also, enemy clerics were priority target. They like to use firestorm and blade barriers, and that's just bad.
If I were to change any one thing, it would be to move the shrine back to the room with the long fall and the first red named giant fight. We were forced to skip the shrine every time to allow the party more time to save the dragon. This just forced more supply use by our clerics/casters and I don't like that kind of plannin by the devs. Already the maze requires some luck to get through quickly enough, add a few seconds to shrine and she is dead every time.