You my friend, are a advertising executive's dream. No, higher octane is not better for an engine.
Here is a little article that basically sums up my beliefs.
http://www.wanderings.net/notebook/Main/IsHighOctaneGasWorthTheMoney
Your best bet us to always use the lowest possible octane fuel that an engine can tolerate. High octane fuel is typically used in engines with high compression ratios, turbos/superchargers, or reccomended by engine manufacturer.