Interesting question.
I think after being with my current girlfriend, who has some major problems, I had to go and learn about a lot of female psychology. Being a teenage girl, from what I have read, is 10x worse than being a teenage male. Also, from all anecdotal evidence, being a female in the range of 30-50 can also be hellacious because you are getting uglier/fatter [which is more important to females] and if you have no partner is even more upsetting psychologically.
So, the only situation that I know of that I may switch with is a really cute or hot 20 something who has tons of freedom to hook up and have fun doing naughty things. But at the same time, being secure with myself. Just having two weeks would be more than enough though. I don't want to go through periods, births and the insane logic that women seem to possess.
In conclusion, I think if all males understood female psychology then most of them would turn down a permanent switch. Being a female is a bitch, literally. It would be fun to see it physically from their point of view, but almost everything else would suck. Maybe I am totally wrong, but thankfully there aren't many females on these boards to kill me [ and my superior logic ;) ]