In the US, will glider clubs let you take up friends in a two-seater if you have a private license? Or do you need a commercial license?
Glider PPL will suffice, did it yesterday and three or four times in the past three months.
That's me in the back seat preparing to take a co-worker for her first glider ride in a Grob-103:
In general, YES.
However, different clubs have different rules, so you will want to check with a given club.