Coming from the CFD world, a lot of the grid meshers have the ability use basic primitive shapes to make a finer mesh in a region of interest where the details are greater.
I thought it'd be really handy to have this feature in this program -- say for instance you have a boxed or cone region in where the details need to be a finer (smaller extrusion width and/or layer height). If there's a print with threads or particularly detailed region (raised picture or logo?), at a particular layer the non-detailed print can be relatively coarse -- and this region slow, with a small width and layer height (I know the layer height option already exists when it's across the whole layer..).
Or if there's a print where in a particular layer, there's a wall that's very think and you want it to be captured with more than just one bead of plastic, the rest of the walls can use a thicker extrusion diameter.
The user could just pick from shapes (box, cone, cylinder, sphere, etc...) and just place/size to specify a region of greater detail.
Also -- I'm not sure if this is already built in, but is there a ramp-up in speed if the nozzle head has to move a greater distance, followed by a slow-down region as it comes near the edge? (Think infill -- if it travels a large distance, accelerate to the midpoint, then begin deceleration until it hits the wall, to minimize overshoot while keeping the print speed up high).