Yeah, there's a huge misconception on what different octanes actually mean. As Arizoni stated, higher octane fuel is only required for higher compression motors. As the octane rating increases in the fuel so does the stability of the fuel itself. Meaning that it takes a higher amount of compression for the fuel to ignite. The reason high octane fuel is required for high compression motors is this: If you ran say 87 octane in a 11.5-1 compression ratio motor, the fuel in the cylinder would ignite before the piston reached the top of it's stroke, forcing the piston back down before it completes it rotation. This is commonly known as "ping".
So to answer your question, being that our motors aren't more than 8.5-1 compression, 87 octane is more than sufficient for our engines to operate efficiently. Though, I will add, that using additives such as Seafoam and Lucas Fuel Additive DO increase the QUALITY of the fuel and eliminate most fuel problems like rough idle and poor performance at WOT. So it a good idea, especially if you have trouble finding a good quality gasoline, to add a few ounces of one of a fore mentioned fuel additives on a regular basis.
Scottie