im a wizard.
Level 45, generally use Magic Missile(+damage rune), Arcane Orb(+damage rune), Diamond Skin(+absorb or +duration run), Blizzard(+snare duration) or Hydra(Venom rune), Energy Armour (+crit chance rune) and Magic Weapon(+damage rune). Swap out either Magic Missile or Arcane Orb for bosses and put Ray of Frost(-AP cost rune) in - Belial dropped so ridiculously fast just pew-pew'ing him with never-ending Ray of Frost.
A 2H is generally better than a 1h+offhand, unless your build is constant spamming of Signature Spells. If you're making heavy use of Arcane Orb, Hydras or Blizzard (or meteor lol), go with a 2H so you get the much larger base weapon damage. A 2H is also alot better with channeled spells than an equivalent DPS 1H - the slower cast speed on a 2H means you tick for higher damage at a slower rate, but it also means you use your AP up slower. Meaning you actually get more DPS over time since you don't run out of AP as fast compared to a 1H.
My Wizard Spell thoughts:
Arcane Orb is by far the best spell - Rune it with Obliteration and watch everything just blow up.
Blizzard is good to use as an AoE Snare (the chance to freeze rune is kinda useless since the snare is more than good enough. Go with with the lingering snare rune until you get the radius increase).
Ray of Frost can be Runed to only use 12AP per second - use a 2H with nice slow cast speeds and you can literally channel that forever without running out of AP meaning you don't even need to use a Signature Spell.
Disintegrate is OK, especially when indoors in tight corridors where you can just pew-pew straight through everything. Biggest downside is that it can't crit (channelled spells don't crit for some reason...), so Arcane Orb beats it for AoE damage and Ray of Frost beats it for single target damage. It has a really cool animation though
Looks even cooler when you put Ray of Frost and Disintegrate and Left and Right mouse and alternate between them
The Hydras (especially the Venom one) are excellent spells to plop down and let it pew pew everything. I was running with a Demon Hunter and was surprised by how much better the Hydras are compared to the DH's turrets. Very handy if you need to kite since you can throw down a Hydra, then run like Benny Hill in circles around the mobs while the Hydra shoots everything.
Meteor is trash, don't bother with it. It becomes marginally useful in a group when a Barb or a Monk is grouping everything up, but the delay before the meteor comes down kills any effective use of it. Blizzard is far more useful. If you really want to use it, probably use it with the Meteor Storm rune since it it hits a larger area making it slightly easier to target...
Magic Weapon is extremely useful - run it with Force Weapon and you get a free 15% damage buff as well as an un-tooltip'd 15% attack speed buff (that could be a bug though). Familiar with Sparkflint is also effective as a self damage buff. Don't forget the Glass Cannon passive either - through nightmare at least the armour/resist debuff it gives you is a non-issue.
Diamond Skin is a must-have. Use it liberally.
Ice Armour is good value early on, but when you get Energy Armour you'll probably use that all the time. The -20AP is not an issue if you use the passive that gives you +20AP and +2AP/s. Plus you can Rune Energy Armour to give either 5% crit chance or remove the -20AP and give +20AP instead.