Haven't made it to 80 yet, but arena'ed alot at 70 (mainly 2v2 as resto).
I would recommend looking at:
http://www.wowhead.com/?talent=hZ0gMhZx0xuixsEkbIRt
Dispel resistance is definitely something you want to max. If they have to blow an extra GCD (or 2) to dispel your shield it gives you a definite edge.
For 2v2 Insta-wolf didn't seem that great to me.
Instead of Insta-wolf and Imp Shields I went extra crit and Sham Focus - we get alot of utility out of crits, plus the 45% less mana on shocks is awesome (I tend to play offensively even as resto).
Imp Healing wave wasn't worth the points to me as I usually spammed LHW. HW was a NS>HW combo usually.
I'm a big fan of Nature's Guardian. It has saved my butt many times.
If you plan on hitting BGs a bit I would take Insta Wolf at the cost of 2 pts in Thundering Strikes.
I really can't wait to hit 80 and go, but from what I hear its pretty rough going for healers in arena right now. I recommend getting as much crafted PVP gear as possible to have some resilience. And I would also get into Wintergrasp everytime it pops so you can hit the raid boss after you win and get some nice PVP epics.
Cheers!