Were it me (and i am actually looking @ Rokinon as well) I would try for a full set of them. However, I would start on the wide end. It's often much easier to move in closer with a wider lens than it is to back away. I'd hold out for a 50mm and then go to something like their 24mm (i think it is?).
For narrative Super-35mm sized work, the 35mm focal length really is a workhorse, so you've got yourself covered there. I would say then, it's much better to go wider from a 35 then longer to an 85.
As for zooms. Meh. not a big fan, and for one I'd rather had a set of lenses which'll all be similar than start to match dissimilar lenses together.