i've done all 3 spec's, and cross specs' a few times and i've gotta say full frost (11ish in arcane at 80) is by far the easiest to get the most dps out of.

just spam frostbolt, (and use pet as often as you can, or just bosses w/e) and you'll get pretty high dps

/assist party1
/cast Summon Water Elemental
/cast Icy Veins
/cast Frostbolt

easy. and with the talents into improved water elemental and the glyph, your pet is up like 1.5 minutes and cd is only like 45 seconds or somethin... so you can almost always have them up.