Like Skeinforge's Jitter, Slic3r has a method of alternating Z-lift points.
You will need the SketchUp model. A magnifier would also be good for looking closely at the surface results.
We will proceed as follows:
In Slic3r, under Print Settings, select Layers and perimeters. Scroll down to the middle and check the Randomizing starting points box.
Print the surface test model using your best setting.