The word gift implies, at least to me, something that is frivolous or unrelated to every day responsibilities. So I’m going to skip over things like tuition, bills, housing, children, etc, because those things to me, are largely responsibilities that will happen somehow anyway (in a good way, of course).
So if I had the money/time/connections, I’d give her/us a trip around the world, which would last for five to seven years. We would stay at any give location for at least three to four months—the typical duration of a semester abroad—which is just enough time to get to know a place. It’s much longer than the average ten day to two week trip, in which sight-seeing, shopping, and eating are crammed in each day.
I know we both have lists of where we want to visit, so we’d probably go to those places first: Egypt, China, Abu Dhabi, Thailand. I’m sure we’d like to stay in Japan for an extended duration as well.