Depends on the class. For DK in vet Dungeons, I like having:
21 Heavy Armor Focus
31 Bastion (fun having 15k shields with maxed resistances)
48 Thick Skinned
49 Hardy
49 Elemental Defender
66 Ironclad
6 Spell Resistance
For other classes, I like having 32 Quick Recovery and an even balance between Heavy Armor Focus and Spell Resistance. Hope that helps
The most balanced cp is 66 ironclad and thick-skinned, 49 elemental defender and Hardy, 4 into spell shield and whatever armor node you are wearing, for heavy it's heavy armor focus and 32 into quick recovery. This will give you 33% damage reduction from everything and like .75% more armor, with 8% more healing received. All my toons have this set up.
Typically you want around 50 CP in the major damage reduction slots (since diminshing returns)--ironclad, thick-skinned, ele defender. For the rest you'll want to allocate based on your stats. You don't want to be above 33k resists (fully buffed) so just dumping points into the physical and spell resistance slots is a bad idea unless you know you need more resists.
Unless you pvp, the third constellation isn't very useful...maybe put a few points in quick recovery, but not many.
You really can't just take someone else's allocation and copy it, not if you want to maximize the efficiency of your red cp's.
You want to be resistance capped for both physical and spell, so see where you're at with gear and hit your major resolve & major ward buffs (hardened armor, balance, w/e) then fine tune your red trees, point by point, into whichever armor focus & spell shield until you're resist capped (33k-ish) when buffed, and work on keeping your buff uptime high in fights.
Then start allocating your other points for hardy, thick skinned, ironclad etc what works for you, same deal as above poster said about not wasting additional points, it rounds DOWN to nearest whole percentage.