I believe that the iridium type plugs allow for a better spark than platinum (more like using a standard copper plug), but provide the errosion resistance of a platinum plug for longevity.
Since I assume the 2.2L is a 4 cyl engine, and therefore should have the 4 spark plugs across the top for easy access and service, Id save the money, use good copper plugs, and change them more often.
I doubt you can do much better than a good copper plug, and the only real benefit that I know of for the other types is that they dont need to be changed as often, saving headache in squeezy v6 engine bays, etc.
JMH