If you have direct admission to CS at UIUC, that is the safest path. However, I saw that you had a 2220 SAT, 780s on Physics and Math 2 SAT II and an unweighted GPA of 3.85, which suggest that competitive admission to the CS major at Washington may not be that much of a concern for you compared to the average student, as you would be well above the top 25% of the class. If I were you, I would call the department and speak with an advisor about your prospects, given your outstanding academic profile. See also:
http://www.washington.edu/news/blog/uw-wins-national-award-for-promoting-womens-participation-in-undergraduate-computing/
Good luck!