If asked in a polite manner
I will comply with the wishes to see my id. Likely I will ask why, and if the answer is reasonable then I will. Generally, I don't flash my drivers license unless asked by a cop. But I have been known to give my business card out to verify my identiity, not fool proof, but useful.
Imagine, if you would, a quick glance at any form of id is just to put a name to the face, for many reasons its a good idea. Security being one of them. I don't think its unreasonable to be safe.
If you are worried about showing your ID, you are going out with the wrong women....