I use the clear "Nexcare" adhesive first aid tape on the undersides of my rulers. Cheap, readily available and see-thru. The tape is textured, so it grips the fabric and keeps it from sliding. I have put it on all my rulers and don't have a problem.
Adhesive backed sandpaper also works well, but is not see-thru.
I had a suction-cup handle and it went into the "give away" pile. Not worth the money.