(Disclaimer: the 24 hours has an option to extend for a longer period of time if whatever you'd like to try would require so. I am not responsible for any misconducts or unwanted things happening due to this limited-period trial of the opposite sex, whether from lack of fitting clothing, balance issues, changes in size, any form of inherited or incurred illness which will manifest, lack of make-up skills, neighbours wondering who you are, police wondering what you're doing in your home when you're not you, or sexual promiscuity. Nah, fuck it, you'll be free of all those problems. Define your own parameters for whatever)
So, yeah, what would you do if you could get a limited period "trial" as the opposite sex? It would be a nice learning experience, for sure. Some would probably find the idea somewhat erotic. And some might not like it at all. What about you?
Honestly, one of the main differences between the sexes, as I see them, is what you get when you drop "es" from sexes. Sex. I'm quite sure there are many interesting small psychological differences to explore, but the first thing I would explore would be the physical ones. I'd probably try to hire in some help from some lesbian friends to intimately teach me about the female body. I know a few, and I'm sure at least one of them would agree to help.

Especially as damn sexy as I would of course be.
After that, I don't know. I might take it a step further and try sex with a man. I'm a curious guy, and I'd probably wreck myself afterwards if I did not take such a once-in-a-lifetime chance.
A 24-hour trial would not allow for much of the psychological and social differences to be explored. I would therefore have to take a month to do these. And if I got the chance, I would pick that long. I'd probably try to immerse myself in whatever female sides I have, and sort of block out my male self to get as good an idea of how the other half of the gender barrier actually lives. It would be an interesting experience. It would also probably be crammed full with things to try out, because I would have only had a limited period to do stuff in. I'm not sure exactly what I'd be doing, but I'm sure if the opportunity arose, I would find something to do.
And no, it would not all revolve around sex.

And Gaijin: You, sir, are a really upstanding and self-sacrificing citizen.