How much does the quality of laminated flooring depend on its thickness?
A lot has been written about this subject. I am of the camp, like Tester 101, that laminate flooring is a poor choice  for kitchens and bathrooms. Keep in mind that laminate flooring is a pressed paper/composite backing with a "picture" of the finish on top. Granted, laminate has come a long way and the surface durability of the better brands is quite good and guaranteed for life.  however, read the warranty carefully. the warranty may cover replacement costs of a damaged piece of flooring, but never the labor cost to replace. Trust me, replacing a few pieces in the middle of a field is no easy task and the results are never as good as the original install. Also check that water damage is covered by the warranty. Most manufacturers only cover surface damage by scratching, not water damage. When water gets between the slabs, it can quickly be absorbed and the flooring will swell and buckle. This kind of damage is not reversible.

If you are sure you want to have a wood type floor in this area, I would encourage you to look at some real wood engineered flooring before making a final selection. Engineered flooring comes in the easy to install click-lock designs, pre-finished,and some with foam underlayment preinstalled.  The key advantage to engineered flooring over laminate is that engineered flooring is all wood. The back is usually a plywood type base with 1/8 to 3/16 inch of real wood veneer on the top.  This makes it sandable and re-finishable should it be necessary. Although it is not perfect for a wet area, it will hold up to a soaking much better than laminate and usually will dry ok and not delaminate from spills that are cleaned up quickly.

Until a laminate  flooring is made to be 100% water proof, I will not use it in kitchens, baths or entryways. I have been burned, even with the more expensive brands. As a result, I will not offer laminates to my customers at all, especially since I can offer engineered products at the same cost with much better looks and results.

I should mention, there are now some fantastic floating vinyl flooring systems out there that look every bit as good as laminate, easy to install, very durable, and most of all, completely waterproof. They are also quite affordable, in the $2.50 to $4 per foot price range. In my opinion, a much better product than laminate for these applications.