japan and mexico are both sweet, it depends on who you go with, where you go and what you wanna do.
i usually go to japan at least once a year. the cheapest times to get flights (this is outa LAX) is february and october... roundtrip airfaire can be as low as $350. you can also get a 2week JR railpass for about $200 which means you can travel the entire country pretty much for that price (there are alot of local trains that aren't JR that you still have to pay for) right now the yen is really strong, 105yen to 1 usd, last year around this time it was 120Y, so it means if you go there, things are even more expensive than they usually are. cheap hotels are as low as $70 and even nicer hotels like the shinagawa prince is only $100 or so if you make reservations in adavance. i usually stay with friends so i usually don't have to figure in those costs.
if you like to club and party roppongi and shibuya are the places to be, especially on the weekends. trains stop at around 1a, so you gotta party until 5a when they start up again
if you wanna see the race shops and stuff, superautobacs is in odaiba, and there's always tons of crazy cars in the parking lot there. the toyota center is across the street and that whole area, called tokyo bay has lots of things to do and see. yokohama is cool, and i also usually take the shinkansen to akita which is northern japan countryside to see some family.
as for mexico, TJ kinda sucks, unless you just wanna go get drunk for cheap and get good tacos. the coolest place i've been there is sanfelipe but that's like 5 hours south of the border by car and there's all kindsa crazy federalis that'll stop you that you have to bribe for whatever stupid reason they're stopping you for. ensenda and rosarita is pretty fun too, but the partying there is all pretty much just getting completely drunk and stupid. there are alot of american run clubs and bars and americans around, especially during spring break or other school vacations like that. mexico is way cheap too, but also kinda poor and dirty is alot areas.
anyway, that's my long 2cents
