Advantages at WSU:
*Smaller classes
*pre med advising committee
Disadvantages at WSU:
*in the middle of nowhere, so very few opportunities to volunteer at a hospital
Since I am actually a senior at WSU, I will share my take. As you can tell by my username, I am getting a BA and a BS, so feel free to ask me about the college of science or liberal arts.
I applied to both UW and WSU when I was in high school and was accepted at both. I ultimate chose to attend WSU based on the professors. On a campus tour of WSU, two professors took me to their research labs and showed me around. They then bought me lunch and passed me to a few grad students. I saw the campus in a way that UW never showed me theirs.
UW is located in Seattle, which some say is a plus. However, I enjoy Pullman (minus Greek row) and the size. For me, college was not about partying or the atmosphere, it was about the school. The science students are way different than the vibe given off by the Greek system at WSU. In fact, we are not a party university. Look at our crime rate! Our crime goes up during the holidays because we get partiers that come to us.
Smaller class sizes is a huge plus (minus the freshman level chemistry and biology courses which have 200-300 students). But I am sure UW has comparable sizes.
As for hospitals, if you want to volunteer in one there is the Pullman Regional Hospital that always accepts volunteers. There is also Health and Wellness, as well as a few in Moscow, ID. There are also many doctors to shadow, but not as many as in Seattle. Take it as you will, but I am content with 150 hour of clinical volunteering I did in Pullman and 80 hours of shadowing.
The Pre-Med office (also called STEM) is really helpful and encouraging. They are in the process of writing my committee letter now! I have been closely tied to them for my entire undergraduate career and Gloria and Kay both know me by name and about my entire family. They keep track of club events and know about other activities in the surrounding area (including a list of medical offices, volunteering locations, healthcare setting practice, etc. for Freshman to use and get in contact with).
WSU is a research institute. I have done research since my Junior year, and most of my friends have done it Freshman year. I am sure UW also gets research funds, and the businesses around them do too, but in my mind that means you will have a lot more competition to get into it. Population of Pullman is 35,000 but the population of Seattle and surrounding area is over a million. Take that as you will. I am sure you would get more healthcare research experiences in Seattle, but PRH started medical research last year and pays the students.
Oh, final plus for Pullman is the cost of living. I live in a super nice house, right next to campus and spend $450 for rent. My previous years I went cheap and only spent $200 a month and then walked to campus/biked/bused depending on the weather.
Cons? I am sure there are a few for both schools. I can't think of any that I have experienced at WSU other than people giving me crap for going here. Your undergraduate experience is only worth as much as you put into it. We just had a student get accepted at Harvard Medical School with a full ride scholarship and he says that WSU helped him get in, but it was mostly his character and drive that caused him to get accepted.