My parents once took me to see The Sound of Music. It must have been well into its run, because Mary Martin was not in it. I do remembering that I loved it, but I did not save a Playbill, to my eternal disappointment. (To this day I have one for every Broadway show that I see, minus a few that were probably misplaced).
When I started attending with a close friend, the first show I ever saw (at 14) was Mary! Mary! The day before our first trek into Manhattan, it had become the 10th longest running show in Broadway history, so it seemed like the one to see. Paid $2.30 (don't ask why I remember) to sit in the second balcony of the original Helen Hayes, a jewel box of a theatre torn down for the Marriott. I didn't really like it, but I remember being entranced by the set, the fact that it was live, and occasional lines. Clearly, I was too young.
The second show I saw with the same friend was Ben Franklin in Paris, which was flop with Robert Preston. I remember enjoying that one quite a bit, though, and there was one genuine show stopper. Next was Funny Girl...Christmas week, standing room bought in advance, and I was hooked forever.