I like having mostly stam skills on the front bar and mostly magicka skills on the back bar. Makes it easy, when you're a little short of either resource, to do a heavy attack to get that resource, then cast what you wanted to cast, without swapping bars.

Another reason I like having Leash on the front bar is that I can taunt the melee target(s), leash something to me, and immediately taunt/fracture/maim it, all without switching bars.

Storm works fine for me on the back bar, next to Surge.

I see that you have trials in mind, but for dungeons, Surge + Storm + Liquid Lightning + Elemental Blockade + Caltrops makes you a one-man wrecking crew, especially if you throw in Ilambris and the destro ulti. It will melt your eyeballs, though.