Very nice, looks like you had a great time. Do you stay within a certain distance from the airport depending on altitude? Do glider folks do cross country flights?
Yes, It's a good idea to stay within gliding distance of the airport, and that does vary with both altitude and wind. You get bonus time for any lifting air masses you can find along the way. Generally, glider pilots will be conservative and calculate their "final glide" back to the airport as roughly 1/2 the rated L/D glider ratio of their plane. This old bird is rated as having a 38/1 glider ratio. Therefore, if I am a mile high, with no wind, I would be able to "safely" stray from the airport by about 19 miles.
Cross country flights are often done with glider planes around the world. There's a daily contest put on where pilots post their flights and compare themselves with others. the Soaring Society of America also keeps records. Currently, here are some examples:
Highest altitude with a glider plane: 76,100 feet (2018, Argentina)
Longest distance travelled by a glider plane: 1869 miles (2003, in S. Africa)
Longest distance travelled by a glider plane in the USA: 1,023 miles (1983, PA to TN)
If you are curious, the Soaring society of America has loads of resources ( SSA.org )