Godzilla, they may be inclined to shift their tactics if they think that going after our infrastructure and our economy would hurt us more. Look at the emphasis in the MSM lately on the price of oil and natural gas, the volatility of supply, especially when the hurricanes in the Gulf shut down production for a while, and the jitters that the public gets every time they think we are going to have to go without.
They may have gotten the impression that we are more vulnerable through our consumption-based economy than through fear for our lives, as demonstrated by the fact that 51% of the country told the pig-lover Osama (may Allah shower hiim with luncheon meat) to get stuffed.
It would be a big shift. This, however, brings us back to the Texas scenario. If they can do a coordinated strike against key points in several facilities, it could both cause a substantial number of casualities as well as impact the economy (which place had the big disaster in the 50's?). But to pick a natural gas pipeline or even several, would bring a low return for the risk involved. They've only got so much resources and would want to maximize them to get the most bang for the buck.