One feature I would be excited about is pockets in the doors (at least fronts), with enough space for an ice scraper and bottle. Umbrella space is an aspiration.
Another is hanger hooks (preferably on all four doors, but at least in the back seats). Backseat pockets is definitely a bonus as well. Backseat cup-holders and 12v/USB(s) would rock as well. Sometimes it is the simple things.
One of the bigger items would be roof rack compatibility regardless of roof type choice, though I'd spring for towing with a bike rack most likely due to aero reduction from a roof rack. Also, I'd love it if the base wheels were 17 inches. More range and tire lifespan are far more important to me than the supposed handling benefits/looks on a base model. Furthermore, compatibility for smaller wheels means better snow handling in the winter.
Chevy's rear-view mirror/camera thing in the Bolt is actually pretty cool, but who knows maybe it is patented. Love the idea of unobstructed and wider viewing angle. They might as well demolish Chevy completely and take away their only good advantage. As far as I see if Model 3 gets towing capabilities, the Bolt's supposed benefit of additional cargo capacity/hatchback style would be reduced to almost nothing.