When deciding on what material to use around your new fiberglass swimming pool you have some options.
The first and most economical option is Concrete.
There are several different types of concrete, the first is a plain blushed concrete, this is the most economical way to add a finish to your pool. It can be installed one of two ways, the first option is Vastec aluminum coping. http://www.vastec-usa.com/
The second is a Styrofoam form that gives you the ability to cantilever the concrete. http://www.stegmeier.com/ . This method increases cost because the forms have to be removed while the concrete is setting. With this process a concrete finisher has to be in the water because fiberglass pools are filled as part of the installation.
Other types of finishes for concrete are stamped or patterned, exposed aggregate (a bit rough on your feet) colored, fan finish.
The price range of concrete is anywhere from $10 to $15 per square foot depending on the finish.
The biggest disadvantage is that if a repair is required, the concrete has to be removed. A difficult and costly repair.
The second option (my recommendation) is paver stones or natural stone. Several different companies make these products I have listed a couple here as an example. http://www.unilock.com/
These companies make a coping stone which can be cantilevered during the installation without entering the pool. You can also install different types of coping, bull nose or rock faced to suit your tastes.
Many different shapes, sizes, colors, patterns are available giving you more selection.
The biggest advantage to this method is that stones can be removed easily and replaced if a repair is necessary.