Getting back in and figuring out builds.

Well,
As I have stated elsewhere, I am getting back into WoW after about a year off. The game has changed a bit since I left and so I am checking on the validity of the following Builds for my toons.
Party Composition:
Pally (tank):http://www.wowhead.com/?talent#scZEM...sIufdxf:pk0cVz
Priest (healer): http://www.wowhead.com/?talent#bVubu...V0hxumo:VbdzVc
Magex2 (dps): http://www.wowhead.com/?talent#of0ic...0rzr0sx:hGmo0M
Warlock (off-tank/dps): http://www.wowhead.com/?talent#IZfGc...uVZicMo:phG0zV
I plan to eventually replace one of my mages for another Warlock, because even specced Demo my lock was outdpsing my mages (and provided a lot more utility too). You only need 1 mage to summon water/etc :)

Are the Glyphs I'm using super rare?
Any thoughts on how to improve DPS?
My goals are PVE only. I have litte/no interest in PVP.

I'd really consider an elemental shaman for a caster group.
They'll bring a lot more then a mage to a boxed group.
Tremor is nice too, for certain encounters.
Heroism is pretty huge at times too.

If you're willing to manage the Eclipse procs.
Or have some kind of macro that does something towards that end.
A balance druid is also huge for a caster group.

Personally, I'd go for one of each, and scrap both mages.
I like the utility the mages bring, but both the shammy and druid bring stronger dps and are easier to box.
MotW > AI, even for a caster group.
I do like the portals on the mages, but not enough to take a mage over either boomkin or elemental.

Frost is probably the lowest dps spec for a mage.
The replenishment is nice for sure.
And they're relatively easy to macro (Frostbolt and Water Elemental).

If you'd like to continue to have one in your team, consider an Arcane spec.
Like Fire, it is a lot more dps then Frost.
Unlike Fire, there aren't constant procs to watch out for (and which if missed hurt the dps a ton).
Arcane would go 4x Arcane Blast and 1x Arcane Missiles.
Not taking the last point in Arcane, if you want 21 elsewhere is decent since you're not using the spell in the dps rotation anyway.
IMO, Polymorph is a wasted glyph. Aside from PvP (which you're not doing), you don't really need the spell much.

I would go dest with the lock, you get replenish and alot more DPS(AFAIK) and go for arcane with the mages. Would be the highest DPS specs and why would you need an offtank anyway?

But if you arnt set on those characters I would put a shaman in instead of the mage(I pretty much did, replaced my boomkin with one anyway) works out alot better.

Well, I am less of an alt-itis type of person than most. And (annoyingly) I become attached to my characters. It actually took me a long time to decide to replace just one of my mages. Considering the time investment necessary to remake all of my macros I'd have to see significant advantages to justify the time it would take to get a new toon to 80 (not doing RAF, nor going to spend the money to do RAF).

Heck, just changing my talent specs is going to take a lot of configuration. I truly wish there was an easier way to do all this!

I currently have 1 level 30ish shaman. Can't say I'm too thrilled with their mechanics. Theorycraft-wise and evidence from others shows that they are pretty much the best all around Healer/DPS class - but replacing toons isn't what I'm looking for. More of a "given these toons, with maybe one mage turning into a warlock how would you guys pick the talents".

As for Off-Tank - the warlock offers an in-combat res (and my skills are poor enough that I like that) and pet tanks where pretty uber when I left WoW against bosses that did lots of AOE damage (since they only take 10% of damage). Not sure if that is still the case, but it sure helped. Oh, and OT can be considered another form of CC that works just about every time.

If you want to keep the mage, then keep the mage.
There's nothing wrong with playing what you enjoy.

I personally really like having at least one shammy in any caster type group.
280 party spell power, casting haste, health or mana regen and tremor totem.
On a mail wearing, shield using caster.
Bloodlust/Heroism is nice, they can dps and heal well enough.
They can rez others and self rez too.

That's not to say your team will not work, or that you cannot clear every heroic with the current group.
A Pally is a pretty good tank, and easy to macro (96969) as a boxed tank.
A Priest is a very good healer. Discipline has a lot of mitigation and Holy has great AoE heals.
The warlock can spec however you like, and with click castsequences will dps well.

The mage mana issue can be mitigated somewhat by having one go Frost, which gets replenishment.
Frost isn't a waste, in that you'll snare things at range and possibly freeze them in place.
Blizzard is an excellent AoE, and the pally is excellent at holding AoE threat.

I'd probably go Arcane on the second mage, just because its a lot easier then Fire.
With Fire, you need to watch for specific procs and then cast a given spell.
Then again, with an addon like MSBT set to display procs etc, you can macro whatever too.

Outside of high level arena, anything can be made to work.
An all caster group (aside from the tank), is especially easy.
Although interact-with-target, has made melee much easier too.
If a given composition is fun, go with it.