Well Earth and Ice have good AoE potential with Quicksand, Volcanic Gasses, Earthquake, Sleet and Ice Storm. Electric, however, doesn't have much to go for in terms of AoE - there's the cone which looks cool and the PBAoE which can knockback. I find that Assault sets don't always go as well together with Controls as Buff/Debuff sets do (I know there are some exceptions like Fiery Assault and Psionic Assault). You just need to find a set that you enjoy.
I'd personally make an Elec/Earth over Earth/Elec.
This seems like a fairly good combo. For my concept, a hero that can summon forth the "primal energy" of the Earth itself, it fits the bill perfect (I already have a controller, so instead of making a /Storm, just gonna go with /Elec and //Ice)
However, not having made a Dominator before... is it any good? I define good as in the powers will mesh somewhat, and not just be a cluster**** of random powers. :P