I flew about twenty hours in gliders many years ago. The mechanics of flying a glider are simpler in many ways than a powered plane: no engine control, usually very little radio communication, lower speed than powered planes, and the lack of engine noise makes for a nicer learning environment. Of course, you need to find rising air to make your flight longer than 10 minutes or so, but since you can't practice landings touch-and-go like the power pilots, many short flights are in order anyway.
A high performance racing sailplane may have a 26 meter wingspan, a top speed of 275 km/hr, and be able to glide 50 miles from an altitude of 5000 feet. Some current world records (all flights must take place in daytime hours only!):
Out and return distance: 2247 km.
Free distance using up to 4 legs: 3009 km
Speed over an out and return course of 500 km: 306 km/
Absolute Altitude: 15,460 m
If you're curious to try a glider ride, and you're in the US, go to
www.ssa.org . Click on "about Soaring" on the left, then "where to fly".
I couldn't find a directory covering other countries, but you might start by looking up your country's sporting aviation organization. You may be able to find some info at the FAI site (International aviation organization), at
www.fai.org/gliding