Kelley has a much better program. University of Washington is not know for its business school. The midwest market is a lot bigger than the pacific northwest. Kelley is a solid business especially good for marketing and with money from Kelley this should be a no brainer.
I disagree here, Foster and Kelly are peer schools. Maybe you can make the argument that Kelley is a hair better, but saying "University of Washington" is not known for the business school is incorrect.
That said, since Kelley gave you money, it's a pretty easy choice.
p.s. A bigger class size is an ADVANTAGE not a disadvantage, so don't worry about that (more companies go on campus, and bigger network). Kelley and Foster are good enough schools that they are able to find just about everyone a high paying job.