I just installed some 12mil laminates on concrete subfloor. It's definately not as warm as carpet, but you can use a very thick cork underlayment for some good insulation. We went with a 6mil cork. Also, you'll lay a vapor barrier (thick black plastic taped at the seams) for the moisture, so it's not an issue anyway. Just make sure that the brand you are buying is approved for below ground installation.