I have an Armor work bench from Rockler that I use a lot. It is 1 1/2" thick with dog holes.

I made all sorts of clamping fixtures, but I just bought my new favorite. It is the Kreg Bench Clamp Base. A simple aluminum base that a Kreg Bench Clamp slips into. You use a 1/2" bolt (Included) through the dog holes and screw on the big flat wing nut underneath.

It holds very well, and does not put angular pressure on the wood table like some methods do. $20 each, I bought two after waiting months to see them on sale, but never happened.

Simple but effective, and you can use any length 1/2" bolt for whatever you may have to bolt it to. The nut remains captive in the wing nut.

Got mine from Peachtree. My Rockler store doesn't carry them.