"지" and "지요"  ending expresse a softer way of saying something, half talking to oneself and half to the listner.

- 그 시절엔 모두가 행복했어요:  Everyone was happy in those days. (plain, direct statement)

- 그 시절엔 모두가 행복했지요:  It seems everyone was happy in those days. (not as direct, like a monologue)

In questions, it carries a tone of confirming something one laready knows, or suggesting  something.

- 내일은 일찍 일어나야 되지?  We have to get up early tomorrow, don't we?  (confirm a fact)

- 이제 그만 가지?  Let's get going, shaell we?  (suggest an action)