I hear the Japanese curriculum is pretty good, although I hear that about any of the language courses offered.
Intensive class was pretty intense: 8:30am-12:30pm 5 days a week; I learned a lot but since you don't really use the language over a longer period of time, you kind of lose it after 2 quarters of regular classes. I would recommend the regular, 3-quarter track in that regards. I only took the intensive track because I couldn't fit it in with bioengineering class scheduling.
Seattle isn't that bad from my experience, but the crime rate is definitely lower in Bellevue. That plus better traffic situations and is cleaner as a whole. Shopping in downtown Seattle is a whole different experience than shopping in Bellevue, for instance.
Walla Walla is a cool place. Washington has a lot of "friendliest town in America" type of awards. XD
They're really prestigious schools that are basically the "top of the line" universities in the United States. They're also an athletic conference. Their application process is extremely selective so don't be disappointed if you get rejected (my graduating high school class was comprised of over 800 students, only 1 made it to an Ivy League school, Cornell). If you have a really personal personal statement, and your grades are high, and you do a lot of extra curricular activities, you'll have a better shot. Friends from a different high school say a good number of their school's students got accepted to Ivy League schools (this a lower-income, more diverse high school; I dunno if that means much though).
If I go to grad school, MIT is definitely one of the places I will apply to since Professor Robert Langer is a super-famous tissue engineer there and he has published a butt-load of scientific research papers. UW's Professor Buddy Ratner pretty much pioneered the biomaterials sector of bioengineering and Robert Langer is another big person in the tissue engineering sector. I met with Dean Kamen (inventor of the Segway and founder of F.I.R.S.T robotics) since he was visiting Seattle for the high school robotics competition last year and he actually used to work with Robert Langer for prosthetic and other tissue engineering projects.
Long story short, great schools, highly selective. Good luck applying!