Mary
I don't think the phrase "gliders don't go anywhere" was meant to mean a lack of duration or range.
Gliders can and have travelled vast distances and remained airborne longer than powered aircraft. Yes.
But and this is the big But, you cannot climb into a glider and take off, set course in a direction chosen three days ago, fly to a pre-planned destination 300 nm away, land, do whatever you wish for two days and fly home at your convenience.
Your 600k distance depends on where the lift is, where and what the weather is doing.
I don't recall many gliders departing Portmoak for a fly out to Eshott or Fishburn or Carlisle for a day trip.
So let's get the distance thing into perspective ref: "don't go anywhere".
Gliding will teach you stick and rudder skills because to stay airborne as long as possible without power you need to fly the aircraft accurately, "ball in the middle etc" and it is a good thing to learn those skills for fuel saving if nothing else.
During a PFL once, I turned into a hill and after a bit of "rock polishing" in a Cessna 152 to plus 100ft I was rewarded with " bloody glider pilots!" But I still couldn't "go anywhere" except to a better choice of field and then only because the hill happened to be there.
Gliding is a way of life, a dedication, team sport, and requires a minimum of winch/tug driver, hooker up, wing tip runner/signaller to get one pilot airborne.
I can drive to my a/c, pull it out, kick the tyres, push the button and go, severely frowned upon activity at a gliding club.
Rant mode off.