Any of the conditions you described will result in worse mileage, no matter what car you drive. To me, driving 70 instead of 60 and not getting the full EPA mileage out of a hybrid is still better than driving 70 in a non hybrid. I run my AC frequently in the summer. I have never dealt with a 27 percent drop in efficiency from using the AC with ECON in my HCH I. More like 5-10 percent at most.

From a purely economical standpoint, you may get more value out of an EX than a hybrid. As you may have picked up from the numerous posts on "whether hybrids save money or not," it will take a few years to recoup the hybrid premium at current gas prices. Of course, if you drive alot of miles each year, you'll recoup the costs sooner than later, and that tax credit will help. And if the s#!t hits the fan with gas prices in the next few years, you'll definitely be happy you picked up the hybrid. Either way, a civic is an excellent choice, hybrid or not. Good luck.