One last consideration - I had initially gone with the Fire tree for my extra points, (mostly to get Pyroblast). But I did my only respec. I didn't like it, it did virtually nothing for me (the fire tree) as my frostbolts were so overpowered comparatively that they did more damage than the stronger fireball spells, and cost less mana. When you've put that many points into frost, you (generally) shouldn't be casting anything else.
I put the points into Arcane instead, and have been very happy with it for a few reasons. I took Improved Arcane Missles which ensures no interruption when I cast this spell, and then Arcane Concentration. AC makes it so that every ten spells or so, you'll hear a crazy sound, alerting you that this procced, and your next spell costs no mana.
The aforementioned Arcane Missles spell is *very* expensive to cast... I invariably cast it as my free spell unless an AoE (Bliz) is called for. To be able to get away with a spell that expensive for free is very nice.
20/0/41
If you look a little deeper in the Arcane tree, you'll see that there are a couple other *sweet* ones you can get. Improved Counterspell - 100% chance of silencing the target?
Awesome vs. other casters, especially those damned locks... :laugh:
Also - although Arcane Meditation (allows 30% of mana regen while casting) seems more like a healer thing, consider that you have chosen a frost mage. You'll already outlast a fire mage in terms of how long you can cast for (frost spells being cheaper than fire), this will make a very noticeable difference even on top of that.
For example - Fire mages have a higher DPS then Frost mages. Kind of. If you and a fire mage burn down some elite together, he will invariably do a little more damage than you can to the target. BUT - if you both were to nail a 'target dummy' until all your mana was gone, the frost mage actually outdamages the fire mage by a considerable amount. Case in point is when we're nailing Bal or Van in Alterac Valley. I always outdamage the fire mages in those contests and I don't even have the Arcane Meditation above... With it as well, you'd likely almost never run out of mana.
A final thought - the reason I think Arc is better is because Fire and Frost are virtually mutually exclusive - you either take Fire, or you take Frost - they don't 'cooperate' all that well. Rather, they
replace each other to a greater extent. While Arcane can actually provide several very sweet abilities that support and enchance your build.