Your chance at getting in to medical school will be pretty much the same from all of these schools. I would pick UW, because it's your state school.
However, as a current UCSD student, I'm obliged to say that your chances of finding EC and (paid) research opportunities at UCSD are hard to beat. The Salk Institute, Burnham Institute, Scripps Research Institute (TSRI), and UCSD itself are like four campuses all within walking distance. Additionally, the first three do not have undergrads, so the spoils are all yours (the Salk takes only UCSD grad and undergrad students). Proximity of Pfizer and about 20+ spin-off biotech companies in La Jolla + UTC do not hurt either.
As far as 'clinical' stuff, there are three hospitals within walking distance from the main campus (Thornton, VA, Scripps La Jolla). The UCSD Hillcrest shuttle comes every 30 mins and takes you to Hillcrest (beautiful downtown SD) which has three more hospitals (Hillcrest, Scripps Memorial, and SHARP) in addition to literally 100+ small private practices (I shadow a urologist here).
As for the campus itself, you will need to come by to see for yourself. We now have the Price center expansion, and for the first time in 40 years, UCSD has a 'campus center' comparable to, if not better than, UCLA's Ackerman Union and Kerckhoff Hall. UCSD is very pre-meddy, so if you're planning on being a hardcore pre-med, you'll fit in perfectly.
I would still pick UW if I was in your shoes ...
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