After some discussions today, a few idea's came to mind about the base. Does it need to be of wood or stone? Perhaps not, possibilities are...
Wood / Stone - Represent the natural environment, requires sculpting and carving to mimic texture. The uneven base would give a more dynamic a-symmetrical pose.
Bathroom Tiles - Thought of putting spider in defensive pose. Something which would occur when encountered in the home. Would give less dynamic stance but polished floor would reflect details.
Scaled city scape - Treated as a comical city, i.e. B movie spider. Would be amusing and would give an area to create an interesting contrast but also show other skills. But this would move away from the museum style of display.
Fabric or material - Scale up fabrics etc that might appear in the home, would be a usefull way to easily communicate the scale.