there apearantly are four ways to use a spell
1= one handed ''throw''
2= "flamethrower" like
3= two handed for greater blast
4= runes for traps(?)
That is kinda nice, but it would be even better if spells had either other "clusters" of spellcasting ways, or just more options. For example, I really wish for some kind of channeling spell. Two-handed, obviously, without ability to move. Like Blizzard in WoW. TES always had a spell named "Ice Storm", and I think that channeling is best way to launch something with that name.
So, for channeling spells...
1 - equip in one hand and press corresponding attack button once: starts channeling. For a few seconds (perhaps depending on your magic skill) nothing happens, except for ominous magickal winds roaring and some spellcasting animation. If you'll move your feet, channeling will stop. Then, after few seconds passed, the spell effect begins to manifest at the point of your crosshair. You can move now, spell will continue to burn. It can be dispelled by, duh, Dispel.
2 - equip in one hand and hold attack button: same as first at start, some charging, I suppose it should be shorter. Then spell manifests, probably in more savage way (flamethrower instead of firebolt, duh). For example, in Ice Storm case, instead of classical "Blizzard" effect with falling pieces of ice, it could be turned into "Icestormthrower", with more weaker particles of ice flying from your hand towards poor victims. Oh, and it shouldn't always be a variation of a flamethrower for all spells - it also can be either standard channeling process, yet with larger-but-less-damaging (or smaller-but-more-painful) area. Or, say, a huge ball of [something], which is thrown like a standard spell, but it is way more powerful, because it is harder to cast. This way of spellcasting should continue to drain your magicka while it is active. And, at least without perk, you shouldn't be able to move while "throwing" channeled spells.
3 - equip in two hands and press attack button once: same as first, but more powerful. It channels longer, though. Probably additional effects, such as magicka, fatigue or health continuing drain should be more pronounced in this variation of spellcasting, not just "more damage". If I want to strike some mage with a lightning, emptying his magickal reserve, and I mean it - this is the way to perform it. Oh, additional knockbacking is welcome.
4 - equip in two hands and hold attack button: same as third, not as second. It continues to drain your magicka and/or health while you are holding the button. You can't move without a perk while using this way of spellcasting. Effect is similar to standard (1 and 3, not 2), but more savage and less controlable. It continues to burn for a while even after you stop holding the button, and yes, it still drains your magicka/health during this (could be lessened/eliminated by skills/perks). Basically, this way of spellcasting should be used when you are totally in need of damage (or something) no matter what.
5 - equip in two hands and press defend button: shockwave. Very ineffective in magicka cost, probably eats at least a half of remaining magicka. Drains noticeable percentage of current health. Basically this is an explosion of spell effect with you at the hurricane's eye. Everyone around you gets both primary spell effect of channeled spell and, also, is knockbacked. Resistable, of course.
6 - equip in two hands and hold defend button: eye of the storm. It channels the spell just as it should in third (not fourth) case, very powerfully but without hurtful side-effects. The difference is that it is centered upon you, excluding yourself from the area of effect.
I don't think that runes-traps way of casting is good with these hypothetic channeling spells. They just feel too "heavy" to me. Traps are fine with standard spells, though.